QUESTIONS  AND  ANSWERS 

ON  THE 

NATIONAL  ELECTRICAL  CODE 


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QUESTIONS  AND  ANSWERS 

ON  THE 

NATIONAL  ELECTRICAL  CODE 

A  KEY  AND  INDEX 
TO  THE  OFFICIAL  CODE 


BY 
T.  S.  McLOUGHLIN 


FIHST  EDITION 
SECOND  IMPRESSION — CORRECTED 


McGRAW-HILL    BOOK   COMPANY 

239  WEST  39TH  STREET,  NEW  YORK 

6  BOUVERIE  STREET,  LONDON,  E.  C. 

1912 


Library 


COPYRIGHT,  1912,  BY  THE 

BOOK  COMPANY 


THE. MAPLE. PKESS. YORK- PA 


PREFACE 

This  is  a  key  and  index  to  the  National  Electrical  Code, 
and  attempts  to  classify  and  interpret  the  requirements  of 
this  Code  in  a  manner  to  make  the  information  more  easily 
accessible  and  more  readily  understood.  It  recognizes  the 
Code  as  the  established  authority,  and  undertakes  to  explain 
its  method,  purpose  and  influence. 

Eight  sections  cover  the  various  classes  of  electrical  fire 
risks.  They  are  entirely  distinct  from  one  another,  so  that 
the  reader  interested  in  Electric  Railways,  for  example,  will 
find  his  subject  assembled  complete  under  Section  Seven. 
Section  9  completes  the  enumeration  of  fire  prevention 
precautions,  with  tables  and  specifications  of  materials. 
It  contains  the  most  important  of  the  Code  tables,  includ- 
ing Table  I,  Allowable  Capacity  of  Wires,  and  others  fre- 
quently used.  Tables  10  to  18  are  original  in  form,  and 
were  compiled  expressly  for  this  book, 

By  the  employment  of  the  question  and  answer  form, 
with  full  face  side  headings  in  the  language  of  everyday 
practice,  it  is  hoped  that  the  valuable  information  of  the 
Code  is  made  available  for  quick  reference,  and  in  a  form 
that  will  leave  no  doubt  in  the  reader's  mind  of  the  proper 
course  to  pursue  in  given  cases.  Definite  answers  to  the 
questions  arising  every  day  are  given,  and  the  exact  por- 
tion of  the  Code  apply 'ng  to  the  statement  is  quoted  as 
an  authority  in  practically  every  instance. 

The  Resuscitation  C  art  as  given,  is  the  latest  form 
from  the  committee  in  charge  of  this  work.  The  methods 
given  may  also  be  used  in  cases  of  drowning,  asphyxiation, 
etc.,  where  breathing  has  apparently  ceased.  It  is  the 
author's  belief  that  measures  for  the  prevention  of  injury 
or  death  from  electricity  have  not  been  given  the  considera- 
tion they  deserve. 

NEW  ORLEANS,  LA. 
August,  1912. 


CONTENTS 


PAGE 

NATIONAL  ELECTRICAL  CODE  AND  ITS  SPONSORS 1 

LIFE  HAZARD 5 

EXPLANATORY 7 

SECTION  ONE 

GENERATORS  IN  GENERAL.     (Questions  1-70) 9-20 

Generators  in  general;  Central  station  wiring;  Central  station 
conduit;  Switchboards;  Lightning  arresters;  Motors  in  general; 
Alternating  work;  Storage  and  primary  batteries. 

SECTION  TWO 

TRANSFORMERS.     (Questions  71-83) 21-26 

Transformers  in  general;  Low-potential  transformers;  High-po- 
tential transformers;  Extra  high-potential  transformers;  Low 
voltage  transformers;  Grounding. 

SECTION  THREE 

OUTSIDE  WORK.     (Questions  84-136) 27-38 

In  general;  Grounding  in  general;  Wires  conducted;  High  ten- 
sion pole  line;  Underground  conductors. 

SECTION  FOUR 

SIGNALLING  SYSTEMS.     (Questions  137-183) 39-48 

Wiring  in  general;  Outside  wires;  Pole  lines;  Wires  in  Cables; 
Wires  supplying  current  to  apparatus;  Protectors  and  instru- 
ments; All  other  systems  except  telegraph  instrument  circuits; 
Reactive  coils  and  condensers;  Ground  wires  in  general;  Wire- 
less telegraph  apparatus. 

SECTION  FIVE 

Questions  184-215      49-54 

Arc  lamps  in  general;  Constant  current  systems;  Incandescent 
lamps  in  series. 

SECTION  SIX 

IDE  WORK.     (Questions  216-770)      55-137 

Wiring  in  general;  Knob  and  tube  work,  all  kinds;  Protection  of 
wires  from  mechanical  injury;  Exposed  knob  and  tube  work; 
Knob  and  tube  concealed;  Non-metallic  flexible  tubing;  Wooden 

vii 

254484 


viii  TABLE  OF  CONTENTS 

PAGE 

moulding  work;  Metallic  protective  systems  in  general;  Interior 
conduits,  all  kinds;  Lined  metal  conduit;  Armored  cables; 
Grounding  armored  cables;  Metal  mouldings;  Grounding 
metal  moulding;  Regulators,  resistance  boxes,  rheostats,  auto- 
starters;  Auto  starters;  Switches;  Circuit  breakers;  Fuses; 
Rosettes;  Cabinets;  Panel  boards;  Theaters  and  moving  picture 
shows;  Outline  lighting;  Electric  signs;  Decorative  lighting 
systems;  Electric  heaters;  Mercury  vapor  lamps;  Fixtures; 
Sockets;  Flex  cord;  Electric  cranes. 

SECTION  SEVEN 
ELECTRIC  RAILWAY  SYSTEMS.     (Questions  771-868) 139-152 

SECTION  EIGHT 

MARINE  WORK.     (Questions  869-910) 153-162 

SECTION  NINE 

NATIONAL  CODE  REQUIREMENTS  ON  WIRE  AND  MATERIAL.     (Tables 

1-31) 163-210 

Number  of  wires  in  rigid  conduit,  Table  32;  Rulas  for  resusci- 
tation from  electric  shock. 

INDEX     .  .211 


THE  NATIONAL  ELECTRICAL  CODE 
AND  ITS  SPONSORS 

The  National  Electrical  Code  is  a  set  of  rules  and  require- 
ments governing  such  electrical  wiring  and  apparatus  as  the 
Insurance  Companies  believe  affect  their  fire  risks.  It  is 
the  standard  authority  in  the  whole  United  States  and  Can- 
ada and  South  American  countries.  Records  show  that 
the  greatest  fire  losses  ever  paid  by  the  insurance  companies 
for  authenticated  "electric  fires"  resulted  where  it  was 
disregarded. 

Despite  a  popular  and  convenient  error,  however,  it 
does  not  ensure  a  good  job  from  the  user's  standpoint.  The 
Code  addresses  itself  first,  last  and  all  the  time  to  the  fire 
risks;  makes  recommendations  on  the  life  risk;  but  is  not 
officially  concerned  at  all  with  economy,  convenience, 
correct  illumination  or  the  ordinary  every-day  reliability  of 
the  work,  except  incidentally.  Wiring  may  be  far  too 
small  for  bright  light,  and  yet  fully  meet  Code  requirements. 
Designers  and  supervisors  who  use  the  National  Electrical 
Code  and  its  inspection  systems  as  a  free  engineering  bureau 
that  will  serve  all  purposes,  are  therefore  sadly  abusing 
their  clients'  confidence.  Short-sighted  central  stations, 
passively  permitting  their  lines  to  be  loaded  up  with  in- 
stallations too  small  for  present  and  future  need,  although 
approved  under  the  Code,  sooner  or  later  regret  their 
inactivity. 

Revised  editions  of  the  Code  have  been  appearing  every 
two  years  in  about  the  month  of  December,  since  the  first 
issue  in  1897.  The  revisions  are  made  by  an  electrical 
committee  of  the  National  Fire  Protection  Association,  after 
being  chosen  from  a  large  number  which  are  usually  read 
and  discussed  at  a  biennial  open  meeting  held  in  New  York 
City.  This  usually  takes  place  in  March  and  is  largely 
attended  by  interested  electrical  men  of  all  kinds.  This 
committee  is  responsible  for  the  technical  composition  of 
the  Code.  The  revisions  are  slowly  and  cautiously  made. 
The  address  of  the  secretary  of  the  committee  is  141  Milk 
Street,  Boston,  Massachusetts.  It  has  a  total  of  22 
members. 


2  QUESTIONS  AND  ANSWERS  ON  THE 

I^s  membership  'is  composed  of  five  official  representa- 
tives from  the  following:  American  Institute  of  Electrical 
Engineers;  National  Electrical  Contractors  Association; 
National  Electric  Light  Association,  chiefly  Central  Station 
men;  American  Street  Railway  Association,  Electrical 
Engineer  of  the  Municipal  Department  of  Electricity, 
New  York  City;  and  17  affiliated  or  kindred  insurance 
organizations,  among  whom  are  the  Underwriters'  Labo- 
ratories; the  National  Board  of  Fire  Underwriters;  the 
National  Electrical  Inspectors  Association,  and  the 
Western  Association  of  Electrical  Inspectors,  both  chiefly 
insurance  inspectors.  The  Canadian  Fire  Underwriters 
Association  of  Montreal,  Canada;  one  from  Chicago, 
Illinois;  one  from  the  Fire  Prevention  Bureau,  New  Orleans, 
one  from  the  South  Eastern  Underwriters  Association, 
Atlanta,  Georgia;  one  at  Syracuse,  New  York; 

And  the  remaining  eight  are  from  New  York,  Boston, 
and  Philadelphia  insurance  organizations. 

The  Associated  Factory  Mutual  Fire  Insurance  Companies, 
31  Milk  Street,  Boston,  issues  its  own  form  of  the  Code  and 
its  own  List  of  Approved  Fittings. 

Interpreters  of  the  Code  throughout  the  country  are 
partially  relieved  from  the  exhaustive  and  sometimes  incon- 
venient tests  desirable  upon  insulated  wire,  apparatus,  and 
devices,  by  the  incorporated  organization  known  as  the 
Underwriters  Laboratories,  207  East  Ohio  Street,  Chicago, 
Illinois.  It  has  representatives  in  all  the  principal  cities 
of  the  United  States  and  semi-annually  issues  a  list  of  its 
approvals,  obtainable  free  on  application  by  those  inter- 
ested. It  makes  a  charge  for  its  examination  and  tests 
necessary  before  approval  is  issued.  These  charges  also 
can  be  had  on  application.  It  announces  that  it  is  not  in 
business  for  profit  and  that  its  chief  financial  support  is 
received  from  the  National  Board  of  Fire  Underwriters, 
which  directs  it.  The  object  is  declared  as  follows: 

"  To  bring  to  the  user  the  one  best  obtainable  opinion  on 
the  merits  or  demerits  of  appliances  in  respect  to  the  fire 
hazard."  Its  great  importance  to  the  electrical  world  at 
large  lies  in  the  fact  that  it  is  recognized  by  the  great 
majority  of  insurance  interpreters  of  the  Code  as  the  only 
official  approval  available.  Practically  all  the  standards 


OFFICIAL  NATIONAL  ELECTRICAL  CODE        3 

for  general  use  are  established  through  its  approvals.  An 
important  and  recent  accomplishment,  made  with  the  co- 
operation of  the  best  known  wire  manufacturers,  was  the 
establishment  of  a  needed  new  standard  for  rubber-covered 
wire,  which  must,  under  1911  specifications,  have  at  least  20 
per  cent,  of  real  rubber  or  equal  in  its  insulating  compound. 

The  National  Board  of  Fire  Underwriters,  137  William 
Street,  New  York  City,  is  the  supreme  and  parent  body  of 
the  insurance  world.  Its  members  are  high  officials  of 
leading  insurance  companies  and  it  keeps  a  benign  and 
fatherly  eye  upon  insurance  risks  as  a  whole  throughout 
the  United  States. 

It  sends  out  a  corps  of  its  engineers  to  cities  and  upon 
their  reports  conclusions  are  reached  rating  them  as  first, 
second  or  third  class,  etc.  Electrical  fire  hazard  is  one  of 
the  items  of  this  rating. 

The  National  Board  officially  endorses  the  code  and  is  the 
finality  in  the  insurance  family  of  National  Board,  Under- 
writers Laboratories,  National  Fire  Protection  Association, 
"and  their  sisters  and  their  cousins  and  their  aunts."  In 
the  last  analysis  it  is  therefore  responsible  for  the  issuance 
of  the  Code,  the  approval  of  the  kind  of  material  it  pre- 
scribes, and  the  fire  risk  character  of  the  installations 
complying  with  the  Code.  The  Code  is  a  gift  horse  from 
the  Board  to  the  country. 

The  enforcement  of  the  Code  is  attained  more  by  the 
natural  wish  of  those  concerned  to  secure  safe  work  than 
any  other  consideration. 

Fire  insurance  policies  contain  a  more  or  less  uniform 
rider  obligating  the  assured  to  comply  with  the  Code, 
which  the  policy  holder  "signs  up"  along  with  all  the  other 
clauses.  Insurance  Companies  at  centers  throughout  the 
country  usually  group  themselves  in  one  form  or  another, 
and  establish  their  own  inspection  department  of  electricity, 
to  carry  out  the  intention  of  the  rider.  In  stubborn  cases, 
violations  of  the  Code  are  penalized,  upon  due  consideration, 
by  extra  charges  upon  the  assured,  and  in  acutely  dangerous 
places  by  cancellation  of  the  policy.  Charges  are  made  in 
accordance  with  the  degree  of  fire  hazard  incurred  by  the 
violation  as  advised  by  the  Electrical  Inspector,  or  as 
deemed  expedient  to  meet  the  situation.  Zealous  insurance 


4        OFFICIAL  NATIONAL  ELECTRICAL  CODE 

electrical  inspectors  sometimes  greatly  disturb  the  tran- 
quility  of  an  insurance  agent.  Mistaken  interpretations  by 
inspectors  sometimes  prove  a  hardship;  but  where  skilled 
engineers  or  contractors  have  the  work  in  hand,  it  is  usually 
argued  out  to  a  correct  conclusion.  There  are  Code  students 
in  all  branches  of  the  business. 

Municipalities  of  New  York,  New  Orleans,  Chicago, 
Boston,  Philadelphia  and  other  cities  and  towns  have 
ordinances  adopting  the  Code  and  sometimes  providing 
penalties  by  police  power  for  enforcement.  Such  changes 
as  are  made  in  the  Code  by  these  municipalities  usually  make 
more  positive  the  fine  print  suggestions  and  also  the  language 
of  the  rules;  and  recently  include  life  hazards. 

Credit  for  the  plan  of  the  original  National  Code  of  1897 
and  for  the  successful  conduct  of  its  affairs  for  many  years, 
as  far  as  it  can  be  given  to  any  one  man  amongst  many,  is 
generally  conceded  to  belong  to  that  veteran  insurance 
man,  Mr.  C.  M.  Goddard,  Boston,  Massachusetts. 


LIFE  HAZARD 

Failure  of  a  lighting  company  to  ground  secondaries  will 
soon  become  an  invitation  for  litigation.  Fortunately, 
progressive  practice  is  ahead  of  discussion  and  many 
secondaries  are  now  grounded  throughout  the  United  States, 
especially  in  centers.  The  highest  conservative  opinion 
obtainable  is  found  in  the  official  expression  of  the  American 
Institute  of  Electrical  Engineers,  which  has  declared  in 
favor  of  grounding  up  to  250  volts  as  being  good  engineering 
practice  and  highly  desirable. 

Whenever  a  person  turns  on  the  current  into  any  kind 
of  an  ordinary  light,  heat  or  power  circuit,  or  portion  of 
a  circuit,  he  should  be  careful  to  see  that  he  is  in  no 
manner  in  circuit  with  the  earth.  This  may  happen  by 
touching  a  water  pipe;  by  moisture  or  dripping  water; 
touching  a  gas  or  radiator  pipe  and  in  several  other  ways. 
If  he  is  in  circuit  with  the  earth,  he  should  not  touch  any 
metal  of  the  electric  system,  especially  if  an  alternating 
current  system  fed  by  high  tension  primaries.  Before 
cleaning  such  fixtures,  the  main  switch  or  other  cut  off 
should  be  opened. 

Therefore  all  cellar  lights,  bath  lights,  and  current  con- 
suming appliances  reached  from  a  ground  floor  of  earth  or 
concrete  should  be  controlled  by  the  highest  grade  of  switches 
with  non-metallic  insulating  covers  and  insulated  handles 
or  buttons.  If  knife  switches  are  used,  the  handles  should 
be  the  only  portion  touched.  The  lights  should  never  be 
turned  on  at  ordinary  metal  shell  sockets,  while  standing  upon 
or  in  circuit  with  the  earth.  Porcelain  or  high  insulation 
sockets  should  be  used  if  no  switches  are  available. 

Precautions  of  this  kind  are  as  important  to  guard  life 
as  many  of  the  others  so  readily  undertaken  to  prevent 
fire. 

Both  dangers  (i.e.,  of  life  and  fire)  are  aggravated  by 
the  presence  of  the  clumsy,  unharmonious,  and  altogether 
unnecessary  combination  gas-electric  fixtures. 

5 


EXPLANATORY 

The  rule  and  paragraph  of  the  rule  in  the  National  Elec- 
trical Code  from  which  the  answer  is  taken  is  specified  in 
almost  every  answer,  and  is  called  a  Reference  throughout 
the  book. 

The  Code  rule  number  at  the  end  of  the  answer  is  imme- 
diately followed  by  the  Code  section  letter  (and  number  if 
any). 
Example: 

The  question  comes  up  on  a  theater  or  similar  job 

"How  many  fuses  may  exit  lights  have  between  them  and 
the  service  fuses?  By  referring  to  our  index  we  find  this 
question  under 

Theater  and  Moving  Picture  Wiring: 

Exit  lights,  page  106 

or  under  another  heading  if  we  happen  to  think  of  same 
instead,  such  as 

Fuses 

on  exit  lights  in  theater,  page  106 

We  easily  locate  the  question  (No.  521)  on  page  106  and 
see  that  the  answer  is 

"Not  more  than  one  set  and  in  cabinet.     o8-t.)" 

If  we  wish  to  follow  up  the  reference,  which  is  Code  rule 
38- 1,  we  find  the  same  information  contained  in  the  following: 

t.    Auditorium. 

All  wiring  must  be  installed  in  approved  conduit,  metal 
moulding  or  armored  cable. 

Exit  lights  must  not  have  more  than  one  set  of  fuses  between 
same  and  service  fuses. 

Exit  lights  and  all  lights  in  halls,  corridors  or  any  other  part 
of  the  building  used  by  audience,  except  the  general  auditorium 
lighting,  must  be  fed  independently  of  the  stage  lighting,  and 
must  be  controlled  only  from  the  lobby  or  other  convenient  place 
in  front  of  the  house.  All  fuses  must  be  enclosed  in  approved 
cabinets. 

Jobbers,  Contractors,  Purchasing  Agents  and  others  check- 
ing up  stock  may  use  the  tabled  form  of  Code  requirements 
as  presented  in  Section  Nine  to  advantage.  The  essential 
differences  between  all  kinds  of  flexible  cords,  for  example, 
are  at  once  apparent. 

7 


8  EXPLANATORY 

The  author  has  created  a  classification  or  grouping  re- 
sembling, but  not  in  all  cases  the  same  as  that  used  by  the 
Code.  Each  of  the  nine  sections  carries  its  own  explanation. 

As  a  ready  reference  book  it  may  be  used  to  advantage 
either  in  conjunction  with  the  Code,  or  without  it. 

The  purpose  of  this  question  book  is  to  endeavor  to  pre- 
sent typical  and  simple,  every-day  questions  that  arise  in 
practical  work,  and,  by  answering  them  in  a  condensed 
form,  help  busy  men  to  correct  and  quick  interpretation  of 
the  Code  to  meet  their  present  needs. 

The  compiler  believes  it  will  be  useful  to  architects,  en- 
gineers, insurance  men,  salesmen,  electrical  workers,  exami- 
nation boards,  college  students  and  the  trade  in  general. 
He  promises  an  improvement  with  each  issue. 

Such  engineering  features  or  questions  as  appear  to  be 
within  the  range  and  scope  of  this  work  will  appear  in  suc- 
ceeding editions. 


SECTION  ONE 

GENERATORS,  IN  GENERAL 

Central  Station  Wiring. 

Central  Station  Conduit. 

Switchboards. 

Lightning  Arresters. 

Generator  Care  and  Attendance. 

MOTORS,  IN  GENERAL 

Alternating  Current  Work. 
Electric  Fans. 

STORAGE  AND  PRIMARY  BATTERIES 


SECTION  ONE 

Section  One  includes  Central  Station,  Dynamo,  Motor 
and  Storage  Battery  Room,  Transformer  Sub-stations  ques- 
tions. References  principally  taken  from  Class  "A." 

GENERATORS 

Under  this  heading  will  be  found  questions  upon  genera- 
tors of  all  classes,  including  Constant  Current,  Constant 
Potential,  Low  Potential  (550  volts  or  less),  High  Potential 
(550  to  3500  volts  inclusive) ;  and  Extra  High  Potential  or 
over  3500  volts. 

IN  GENERAL 

Following  questions  apply  to  all  kinds  of  generators  ex- 
cept where  specifically  indicated,  as  in  No.  6. 

1.  Are  Generators  allowed  in  wet  places? 
No.     (i-a.) 

2.  Can  a  Generator  be  located  in  a  gas  house,  powder 
factory,  lint  room  of  a  textile  mill,  or  similar  place? 

No.     (i-b.) 

3.  Give  reading  of  name  plate  required  by  Code  on  gen- 
erators. 

Maker's  name ;  capacity  in  volts  and  amperes ;  nor- 
mal speed  in  r.p.m.  ( i-e.)  Applies  equally  to  motors,  with  ad- 
dition for  varying  speed  alternators.  See  question  No.  61. 

4.  Is  slate,  marble,  porcelain  or  other  approved  material 
obligatory  for  terminal  blocks? 

Yes.     (i-f.) 

5.  When  are  properly  filled  hardwood,  porcelain,  or 
micanite  bushings  obligatory  on  generator  frames  for  lead 
wires? 

Only  when  rubber  bushings  are  subject  to  chemical 
action  from  oily  vapors  or  other  agencies,  (i-g.) 

6.  Must  Constant  Potential  Generators  (Alternators  and 
their  exciters  excepted)  be  protected  from  an  excess  of  their 
own  current,  and  how? 

Yes,  by  approved  design  circuit  breakers,  safety  fuses 
or  other  similar  devices,  (i-d.) 

11 


12          QUESTIONS  AND  ANSWERS  ON  THE 

7.  Is  single  pole  fuse  or  circuit-breaker  sufficient  on  a 
two-wire  direct-current  generator. 

Yes ;  provided  it  is  not  in  series  winding  lead,     (i-d.) 

8.  Where  two  generators  are  coupled  in  a  three-wire 
direct  current  system,  or  where  equalizers  are  used  with  3 
wire   generators  how  must  excess   current  protection   be 
given? 

By  a  fuse  or  safety  device  in  each  outside  lead  from 
armature ;  or  by  a  double  pole,  double  trip  circuit -breaker 
used  for  each  outside  generator  lead  and  equalizer  con- 
nection, (i-d.)  Following  contemplated  changes  will 
perhaps  be  enforced  in  essentials  in  1913  Code. 

"For  two  wire  D.  C.  generators,  single  pole  protection  will  be 
considered  as  satisfying  the  above  rule,  provided  that  the  safety 
device  is  so  located  and  connected,  that  the  means  for  opening 
the  same  is  actuated  by  the  entire  generator  current,  and  the 
action  thereof  will  completely  open  the  generator  circuit.  If  a 
generator,  not  electrically  driven,  has  one  terminal  grounded, 
the  safety  device  above  mentioned  must  be  placed  in  the 
grounded  lead 

For  three  wire,  direct  current  generators,  compound  or  shunt 
wound,  a  safety  device  must  be  placed  in  each  armature  lead  and 
so  connected  as  to  receive  the  entire  current  from  the  armature. 
Fuses  will  not  be  acceptable.  The  safety  devices  must  consist  of 
either 

1 — A  double  pole,  double  coil  overload  circuit  breaker. 

2— A  four  pole  circuit  breaker  connected  in  the  main  and 
equalizer  leads  and  tripped  by  means  of  two  overload  devices 
connected  one  in  each  armature  lead. 

The  safety  devices  above  required  must  be  so  interlocked  that 
no  one  pole  can  be  opened  without  simultaneously  disconnecting 
both  sides  of  the  armature  from  the  system." 

9.  Must  Generators  of  550  volts  or  less  be  insulated 
from  ground  where  possible? 

Yes.     (i-c.) 

10.  When  a  standard  filled  wooden  base  frame  (depended 
on  for  insulation)  is  omitted,  and  wooden  floors  are  relied 
oh,  what  requirement  is  made  for  550  volts  or  less? 

Floor  must  be  kept  filled  and  clean  and  dry.     (i-c.) 

Note  No.  1 :     A    heavy   soaking  application  of  linseed  oil  is 
acceptable  as  a  filler  under  ordinary  conditions. 

1 1.  When  insulation  of  frame  from  ground  is  impracti- 
cable on  550  volts  or  less,  what  must  be  done? 

Written  permission  secured  from  Insurance  Depart- 
ment having  jurisdiction;  and  frame  must  be  permanently 
and  effectively  grounded,  (i-c.) 

12.  Must  generators  over  550  volts  be  grounded? 
Yes,  permanently  and  effectively,     (i-c.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      13 

13.  What  is  the  safeguard  suggested  by  the  Code  for 
high  potential  generators  and  machines  of  any  kind? 

"If  desired,  high  potential  machines  may  be  surrounded 
by  an  insulated  platform,  made  of  wood,  mounted  on  insulating 
supports,  and  so  arranged  that  a  man  must  always  stand  upon 
it  in  order  to  touch  any  part  of  the  machine."  (Fine  print 
note  i-c.) 

Applies  equally  to  motors. 

Central  Station  Wiring. 

Following  questions  apply  to  Central  Station  work  of  all 
kinds  as  designated  in  question  or  by  heading.  For  require- 
ments for  wiring  conditions  the  same  as  in  ordinary  build- 
ings, see  Section  Six  (6),  principally  Code  Class  "C" 
references,  for  example  see  No.  249. 

14.  What  insulation  is  required  on  550-  to  3500-volt 
(or  over)  wires? 

Rubber  covered.  (2-b.  and  44 -a).  Read  Tables 
5,  6,  7,  8. 

15.  How  must  open  work  550-  to  3500-volt  wires  be  run? 
Rigidly  supported  on  glass  or  porcelain  insulators, 

kept  8  in.  apart,  and  i  in.  from  surface  wired  over  at  least. 
(44-c.)     Exceptions  for  motors.     See  53. 

1 6.  In  Central  Station  exposed  circuits,  what  extra  pro- 
tection is  required  for  conductors? 

Must  have  heavy  braided  non-combustible  covering, 
(Type  letter  S-BW  wire  covers  this  in  dry  places)  [2-b.] 
Read  No.  53.  [See  Table  No.  2,  Section  9.] 

17.  What   is   the   type   letter  prefix  for    expressing   a 
National    Code    standard    lead-covered   cable   for   interior 
work,  any  voltage? 

R.S.L.(so-j.)     Example: 

zero  to    600  volts  expressed  R.S.L.-6oo. 
zero  to  1500  volts  expressed  R.S.L.-iS. 
zero  to  2500  volts  expressed  R.S.L.-25. 
Prefix  applies  to  both  the  taped  and  braided  kinds. 

1 3.  What  must  be  done  where  wires  are  bunched  close 
together,  as  at  switchboard? 

Must  be  provided  with  a  non-combustible  type  outer 
cover.  (2-b.) 

Note  No.  2:  Flame  proof  cable  covering,  or  type  S.  B.  W. 
wire  acceptable. 


14          QUESTIONS  AND  ANSWERS  ON  THE 

19.  Give  rule  for  conductors  from  generators  to  switch- 
board, rheostats  or  other  instruments. 

Must  be  in  plain  sight  or  readily  accessible.  They 
may  be  placed  in  a  run -way  in  the  brick  or  cement  pier 
on  which  the  generators  stand.  When  such  conductors 
are  subject  to  moisture,  lead -covered  cable  or  iron  conduit, 
with  approved  type  wires,  must  be  used.  (2-a.) 

20.  Is  it  obligatory  to  strip  back  flame-proof  covering 
required  on  switchboard  cable  to  obtain  the  insulation  dis- 
tance between  conductors  required? 

Yes.     (2-b.) 

Note  No.  3:    For  distance  required,  see  table  No.  29,  Sec.  9. 

Central  Station  Conduit. 

21.  What   special   kind   of   conduit   is   required  where 
groups  of  wires  between  rheostat  contact  plates  and  resist- 
ances are  liable  to  mechanical  injury  or  moisture? 

Approved  lined  conduit,  or  its  equivalent.     (4-c.) 

Note  No.  4:    Equivalent  may  be  secured  by  use  of  unlined 
conduits  reinforced  with  flexible  tubing. 

22.  How  must  the  unlined  metal  conduit  where  used  on 
550  to  3500  volts  motors  be  installed? 

With  approved  outlet  bushings  and  otherwise  as  re- 
quired for  the  highest  grade  of  conduit  work.  (8-b.)  Read 
question  No.  53. 

Note  No.  5:    Pot  heads  and  approved  devices  are  acceptable 
instead  of  bushings. 

23.  How  must  conduit  be  bonded  in  motor  leads? 

To  metal  casings  of  all  fittings  and  apparatus  on  the 
inside  of  secondary  or  high  tension  circuit.     (8-b.) 
Switchboards. 

24.  What  is  the  limit  upon  approved  enclosed  fuses  ac- 
cepted for  protection  of  instruments   or  pilot   lights   on 
switchboards? 

Two  amperes.     (2-e,) 

25.  May  busbars  be  of  bare  metal? 
Yes.     (2-b.) 

26.  Are  link  fuses  approved  for  switchboard  work? 
Yes.     (23-c.) 

27.  Is  wood  acceptable  for  a  switchboard? 

Yes,  if  rilled  hardwood  in  skeleton  form.     (3-b.) 
• 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      15 

Note  No.  6:  "Skeleton  form"  is  a  form  of  wooden  construc- 
tion where  appliances  are  mounted  on  their  own  bases,  of  non- 
combustible  material,  and  are  applied  to  the  switchboard  by 
separate  supports. 

28.  What  extra  requirements  apply  where  wood  is  used 
for  switchboards? 

Not  only  must  appliances  be  separated  from  board 
by  non-combustible,  non -absorptive,  insulative  material,  but 
wires  and  current -carrying  parts  must  also  be  separated  in 
similar  manner.  (3-b.) 

29.  Must  switchboards  be  kept  from  moisture? 
Yes.     (3-d.) 

30.  How  must  the  circuit  connecting  ground  detectors, 
pilot  lights  and  potential  transformers  on  switchboards  be 
run? 

With  not  less  than  No.  14  B.  &  S.  wire;  conductors 
must  be  protected  by  approved  fuses ;  must  not  carry  over 
660  Watts.  (2-e.) 

31.  When  may  switchboards  be  placed  against  the  wall 
with  no  space  between? 

Only  when  wiring  is  entirely  on  face  of  board.    (3-c.) 

32.  Is  it  compulsory  to  use  ground  detectors,  except  on 
permanently  grounded  wires,  in  a  power  plant? 

Yes.     (7-a.) 

33.  May  switchboards  be  built  up  to  the  ceiling? 
No,  3-ft.  space,  if  possible,  is  demanded.     (3-a.) 

34.  Can  space  back  of  board  be  used  for  storage  pur- 
poses or  filled  with  rubbish? 

No.     (3-a.) 

35.  If  wired  on  back,  how  much  clear  space  is  obligatory 
between  wall  and  current- carrying  parts  of   apparatus  on 
board? 

Eighteen  inches.     (3-c.) 
Lightning  Arresters. 

36.  Give  number  and  location  of  lightning  arresters  re- 
quired on  power  plant? 

Must  be  placed  on  each  wire  of  every  overhead  cir- 
cuit connected  with  the  station.  Must  be  located  in  readily  ac- 
cessible places  away  from  combustible  material,  and  as  near 
as  possible  where  wires  enter  building.  (5  a  and  b.) 

37.  What  does  the  term  "readily  accessible"  in  answer 
to  question  No.  36  mean? 


16          QUESTIONS  AND  ANSWERS  ON  THE 

Easily,  but  not  necessarily  quickly  reached. 

38.  How  much  insulation  from  ground  or  other  conduc- 
tors must  choke  coils  and  attachments  part  of  lightning 
arrester  systems  measure? 

At  least  equal  to  insulation  resistance  of  other  points 
of  circuit  in  the  station.     (5-d.) 

39.  How  much  conductivity  must  ground  connection 
with  wire  or  metal  have  for  lightning  arrester? 

Equal  to  No.  6  B.  &  S.  copper.     (5-c.) 

40.  May  ground  wires  be  run  inside  iron  pipes? 
No.     (5-c.) 

41.  Must  ground  connections  be  in  a  straight  line? 
Yes,  as  near  as  possible.     (5-c.) 

42.  Can  any  lightning  arrester  not  under  list  of  approved 
fittings  be  used? 

No.     (82-a.) 
Generator  Care  and  Attendance. 

43.  Is  a  competent  man  required  where  generators  are 
operated? 

Yes.     (6-a.) 

44.  How  must  oily  waste  be  kept? 
In  approved  waste  can.     (6-b.) 

45.  How  often  must  it  be  removed? 
Daily.     (6-b.) 


MOTORS  IN  GENERAL 

Note  No.  7:  Motors  in  general  take  practically  the  same 
classification  and  same  questions  apply  as  far  as  grounding 
and  general  protection  is  concerned  as  generators. 

Following  questions  apply  to  motors  as  indicated,  also  22, 
61  and  made  on  248  exception. 

46.  How  must  all  motors  be  marked? 

Name  plate  with  maker's  name;  capacity,  volts  ai 
amperes;  and  normal  r.p.m.     (8-h.) 

47.  How  must  single-phase  motors  be  protected? 

By  approved  fuses,  or  at  least  on  one  side  with  cir- 
cuit breaker  on  the  other.     (23-f.) 

48.  What    special    protection    is    required    for    motor 
circuits? 

Unless  subject  to  competent  supervision  or  on  main 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      17 

switchboard,  an  approved  fuse  must  be  used,  even  if  auto- 
matic overload  circuit -breakers  are  installed.     (23-f.) 

Note  No.  8:     Competent  supervision  must  not  be  confused 
with  an  occasional  inspection. 

49.  What   protection  is   required   for   all   motors   and 
their  resistance  boxes? 

Plainly  indicating  "on  or  off"  switch,  properly  in- 
stalled and  cut-out  with  proper  fuses.  (8-c.) 

Exception:  Electric  crane  motor.  Also  that  automatic 
circuit  -breakers  instead  of  main  switch  and  cut-out  are 
acceptable,  when  of  proper  size,  kind  and  adjustment.  For 
alternating -current  motors  see  also  questions  No.  57  to  62. 

50.  What   type   of   motor   is   recommended   in   dusty 
places  instead  of  wooden  boxing  enclosure. 

Enclosed.     (8-f.) 

51.  Is  a  water-proof  cover,  such  as  oil  or  canvas,  neces- 
sary when  motor  is  not  in  use? 

Yes.  Readily  accessible  dust-proof  and  ventilated 
enclosure  such  as  one  constructed  with  glass  sides  so  that 
motor  may  always  be  visible,  may  be  required  by  insurance 
department  having  jurisdiction.  (8-f.) 

52.  Must  base  frames  on  less  than  550  volt  motors  be 
permanently  grounded? 

Must  be  thoroughly  insulated  from  ground  wherever 
feasible.  Insurance  Department  having  jurisdiction  may 
require  grounding  if  insulation  is  unpracticable.  (8-a.) 

53.  What    kind    of    protection    must    be    given  motor 
wiring,  on  high  potential  systems? 

Metal  sheathed  approved  multiple  conductors ;  metal 
sheath  permanently  and  effectively  grounded;  and  con- 
duit construction  complete  except  that  at  outlets  approved 
outlet  bushing  shall  be  used  instead  of  boxes.  (8-b.)  Read 
Nos.  22  and  23. 

54.  May  ordinary  adjustable  speed  motors,  alternating 
or  direct  current,  be  started  on  a  weakened  field? 

No.     (8-j.) 

55.  When  may  single-pole  switches  be  used  to  control 
motors? 

When  motors  are  i  /4  h.  p.  and  less  and  voltage  does 
not  exceed  300.  (8-c.) 

Forbidden  when  used  for :  Service  switches,  out-door  sign, 
2 


18          QUESTIONS  AND  ANSWERS  ON  THE 

3 -wire  neutral,  (except  in  2 -wire  tap  of  not  more  than  660 
watts.)     [24-c.] 

56.  What  is  the  limit  for  a  set  of  small  motors  grouped 
on  one  set  of  fuses  in  a  circuit  whose  3-  or  2- wire  maximum 
is  250  volts? 

Six  amperes.     (23-d.) 

Alternating  Current  Work.     Read  also  reading  matter  over 
Table  No.  One,  Sec.  9. 

57.  What  portion  of  table  of  wire  sizes,  using  rubber- 
covered  wire,  given  under  section  nine  (9)  (and  National 
Code  Class  "C")  applies? 

Carrying  capacities  under  Table  "B"  except  when 
time  element  circuit  breakers  only  are  used.  (23-6.) 

58.  How  are  sizes  of  wire  determined  for  varying  speed 
alternating-current  motor  leads  or  branch  circuit? 

"The  current  used  in  determining  the  size  of  varying 
speed  alternating  current  motor  leads  or  branch  circuits  must 
be  the  percentage  of  the  30 -minute  current  rating  of  the 
motor  as  given  for  the  several  classifications  of  service  in 
the  following  table :  (8-b.) 


Classification  of  services 

Percentage  of  current 
rating  of  motor 

Operating  valves,  raising  or  lowering  rolls, 
tool  heads,  etc. 
Hoists,      rolls,      ore      and      coal-handling 
machines. 
Freight  elevators,  shop  cranes  

200 

180 
160 

Passenger  elevators  

140 

Rolling  tables  pumps 

120 

59.  When    conductors    would    be    over-fused    for    real 
starting  current  under  Section  9,  Table  1,  [reference  National 
Code  Class  "C, "]  is  an  exception  made,  and  how? 

Yes,  wires  must  then  be  increased  or  adjusted  to  such 
a  size  as  to  be  properly  protected  by  the  fuses  against  undue 
heating.  (8-b.) 

Note  No.  9:  As  a  general  rule,  fuse  and  circuit  opening 
devices  must  always  be  guaged  to  protect  the  wire  first  and 
the  apparatus  next  from  undue  heating.  (8-b.) 

60.  How  much  more  than  actual  motor  rating  must  an 
alternating  current  motor  circuit  or  lead  carry? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      19 

Minimum    same    as    direct    current — 25    per    cent. 
(8-b.) 

Note  No.  10:  In  alternating  current  work,  circuit  may  require 
guaging  enormously  above  a  full  load  rated  current,  for  a  start- 
ing load.  Until  types  and  standards  are  arranged  by  agree- 
ment or  evolution,  each  case  will  be  treated  on  its  own  merits. 
A  reliable  manufacturer's  guarantee  of  the  time  duration  of 
the  starting  current  may  be  used  as  a  basis  of  calculation  in  large 
installations.  Or,  actual  experiment  will  reach  a  correct 
conclusion. 

6 1.  How  must  all  varying  (or  variable)  speed  alternating- 
current  motors  be  marked? 

With    maximum    current    they    can    carry    for    30 
minutes,  starting  cold.     Exceptions :  Railway  service  motors. 
(8-h.) 
Electric  Fans.     55  and  56  apply. 

62.  How  must  electric  fan  motors  be  insulated  from  the 
ceiling? 

By  insulating  hooks  or  substantial  insulators  inter- 
posed between  fan  and  ceiling.     (8-g.) 

63.  May  flexible  cord  be  used  in  wiring  ceiling  fans? 
Yes.     (32-d.) 

Read  also  No.  673,  Section  6,  Division  5. 

64.  What  kind  of  portable  cord  must  be  used  for  rotary 
fans? 

Type  letters  "P.O."  also  "P.  Wp."  and  "P"  according 
to  conditions.     See  tables  Section  9. 

STORAGE  AND  PRIMARY  BATTERIES 

65.  Must  the  same  regulations  where  light  and  power 
current    is    taken    from    secondary    batteries    or    primary 
batteries   be   observed   in   producing  the   same  results  in 
voltage  and  amperage? 

Yes.     (zo-a.) 

66.  What  provision  is  required  for  a  storage  battery 
room? 

Must  be  thoroughly  ventilated,     (ic-b.) 

67.  What  kind  of  wire  must  be  used  where  acid  fumes 
exist? 

Either    weather    proof    or    rubber    insulated.     (26- 
i  and  j.) 

68.  Is  it  necessary  for  secondary  batteries  to  be  mounted 


20          OFFICIAL  NATIONAL  ELECTRICAL  CODE 

on  non-combustible,  non-absorptive  insulators,  such  as  glass 
or  thoroughly  vitrified  and  glazed  porcelain? 
Yes.     (lo-d.) 

69.  Are  metal  connections,  liable  to  corrosion,  such  as 
zinc,  acceptable  for  cell  connections  in  secondary  batteries? 

No.     (lo-e.) 

70.  How  must  wires  be  treated  in  storage  or  primary 
battery  rooms  where  the  acid  fumes  are  apparent? 

Rigid  support,  rubber -covered  wire  or  weather-proof. 
(26  i  and  j.)  Section  6,  Division  i,  Question  254,  also 
applies. 


SECTION  TWO 

TRANSFORMERS  IN  GENERAL 
LOW  POTENTIAL  TRANSFORMERS 

(Air  Cooled.) 

HIGH  POTENTIAL— 550  TO  3500  VOLTS 
EXTRA  HIGH  POTENTIAL— OVER  3500  VOLTS 

Tests  In  General. 

LOW  VOLTAGE  TRANSFORMERS 
GROUNDING 


21 


SECTION  TWO 

TRANSFORMERS  IN  GENERAL 

Questions  apply  to  transformers  of  all  kinds  and  classes, 
except  where  specifically  indicated  by  heading  or  other- 
wise. References  are  from  Code  Classes, "A,"  "B,"  "C" 
and  "D." 

For  questions  upon  secondary  and  primary  wires  read 
No.  84-104  inclusive;  107-136  inclusive,  and  Section  No.  3, 
references  Code  Classes  "B"  and  "C." 

Note  No.  11:     Only  experienced  men  should  undertake  any 
work  on  transformers  while  current  is  on. 

Following  questions  apply  to  stationary  transformers 
inside  of  buildings  and  attached  to  same. 

71.  Where  must  station  transformers  be  installed? 

So  that  smoke  from  coils  or  oil  boiling  over  can  do 
no  harm,  (n-a.) 

72.  Must     central     and     substation    transformers    be 
grounded? 

Yes,  casings.  Exception:  Thoroughly  insulated 
transformers  used  to  supply  current  exclusively  to  switch- 
board instruments,  (n-b.) 

73.  May  transformers  be  installed  in  ordinary  buildings 
without    permission    of   the   insurance  department  having 
jurisdiction? 

No.     (i4-a.)     And  Rules  36  and  45. 

LOW  POTENTIAL  TRANSFORMERS 

Low  Potential  is  Code  classed  (550  volts  to  10  volts)  either 
when  First,  primary  current  does  not  exceed  3500  volts,  or 
Second,  if  primary  wires  3500  volts  to  5000  volts  are  installed 
either 

(a)  Completely  underground.     Italics  page  42  in  Code. 

(b)  According    to  Section    No.    3,    Code   Class    "B"  for 
outside  work,  rule  No.  13  requirements. 

Motor  allowance  605  volts,  (Italics,  page  42  Code.) 
Following   questions  apply  on  transformers   whose  pri- 
maries or  secondaries  do  not  exceed  550  volts. 
Air  Cooled. 

23 


24          QUESTIONS  AND  ANSWERS  ON  THE 

74.  May    apparatus    or    fittings    embodying  air-cooled 
transformers  be  used  without  special  examination  and  ap- 
proval? 

No.     (36-a.)     (Italics.) 

Note  No.  12:  special  examination  and  approval  is  secured 
at  a  standard  laboratory,  per  36-a.  italics. 

75.  Can  transformers  be  placed  inside  ordinary  buildings 
if  the  primaries  or  secondaries  exceed  550  volts? 

No.  .  (36-b.) 

76.  How  must  transformers  be  mounted? 

At  least  a  foot  away  from  combustible  material,  or 
separated  by  wider  marble  or  similar  slab.     (36-c.) 

HIGH  POTENTIAL— 550  TO  3500  VOLTS 

Questions  apply  to  transformers  supplying  secondaries  of 
over  550  volts  and  less  than  3500  volts;  more  particularly 
to  the  transformers  themselves. 

77.  How  close  to  point  at  which  primary  wires  enter 
enclosure  must  transformer  be  located? 

Close  as  possible.     (45 -a.) 

78.  Is  it  necessary  to  place  550  to  3500  volt  transformers 
in  a  fire-proof  and  locked  enclosure? 

Yes.     (45-b.) 

79.  Does  the  Code  limit  access  to  transformer  room  or 
enclosures  to  responsible  parties? 

Yes.     (45-b.) 

80.  Must  transformer  house  be  practically  air- tight? 
Yes,  except  that  it  must  be  thoroughly  ventilated  to 

outside  air  if  possible  through  chimney  or  flue.     (45  -c.) 

EXTRA  HIGH  POTENTIAL— OVER  3500  VOLTS 

Primary  wires  forbidden  in  all  buildings  except  power  and 
sub-stations. 

Secondaries,  unless  primaries  are  underground,  or  they 
otherwise   comply  with   Rule  No.  13  Code  Class  "B"  for 
outside   wiring,   take  high  potential  requirements.     (47 -a 
and  48-a.)     Read  questions  No.  118  to  135  inclusive. 
Tests  in  General. 

8 1.  What  tests  must  transformers  sustain? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      25 

"Must  be  constructed  to  comply  with  the  following: 

1.  Shall  be  run  for  a  sufficient  time  to  reach  a  prac- 

tically constant  temperature  at  full  rated  load, 
and  at  the  end  of  that  time  a  rise  in  temperature, 
as  measured  by  the  increase  in  resistance  of  the 
windings,  shall  not  exceed  50°  C.  (122°  F.). 

2.  When  heated  to  normal  full  load  operating  tem- 

perature, the  insulation  of  transformers  shall 
withstand  continuously  for  one  minute  a  dif- 
ference of  potential  (alternating)  between  prim- 
ary and  secondary  coils  and  between  the  primary 
coils  and  the  core  according  to  the  following 
table: 
Primary  or  Secondary  Test  Voltage 

Voltage 

Not  exceeding  400  volts  1,500 

From  400  to  550  volts  2,000 

Over  550  volts  To   follow   the 

standardization  rules 
of  the  American  Insti- 
tute of  Electrical  En- 


LOW  VOLTAGE  TRANSFORMERS 

Transformers  fed  by  low  potential  circuits  and  delivering 
10  volts  or  less.  Should  bear  approval  of  standard  Labor- 
atories to  use. 

For  primary  wiring,  questions  inside  ordinary  building,  see 
Section  Six,  [or  Code  Class  "  C,"  Inside  Work.]  For  second- 
aries Section  No.  4.  [Signal  System  or  Code  Class  "E,"] 
under  which  ordinary  bell  wiring  is  permitted. 

GROUNDING 

82.  Must  high  potential  transformers  be  grounded  or 
insulated  from  ground? 

Must  either  be  permanently  and  effectively  grounded 
or  permanently  and  effectively  insulated.     (45  -c.) 

83.  Must  transformers  outside  of  buildings  be  grounded? 


26      OFFICIAL  NATIONAL  ELECTRICAL  CODE 

Following  note  from  Code  Class  "B"  (outside  work) 
applies : 

"Where  transformers  are  to  be  connected  to  high  voltage 
circuits,  it  is  necessary  in  many  cases  for  best  protection  to 
life  and  property,  that  the  secondary  system  be  permanently 
grounded,  and  provision  should  be  made  for  it  when  the  trans- 
formers are  built."  14. 


SECTION  THREE 

OUTSIDE  WORK 

IN  GENERAL 

Grounding  in  General. 

Underground  Conductors. 

Wires — Conduited. 

High  Tension   (Constant  Potential)   Pole  Lines  Over  5000 

Volts. 
In  General  on  5000  Volts  Constant  Potential. 


27 


SECTION  THREE 

OUTSIDE   WORK 

Light,  Power  and  Heat.     (For  Signalling  Systems,  see  Sec- 
tion 4,  Code  Class  "E"). 

Unless  indicated  by  heading  or  otherwise,  questions  ap- 
ply to  all  kinds  of  outside  work.  References  principally 
from  Code  Class  "  B"  Questions  Nos.  84,  85,  88,  96,  97,  and 
with  Rule  12  are  applicable  to  all  systems  and  voltages. 

IN  GENERAL 

84.  In  splicing  two  pieces  of  wire,  either  inside  or  out- 
side wiring,  what  precautions,  must  be  taken? 

Must  be  spliced  or  joined  so  as  to  be  both  mechanically 
and  electrically  secure  without  solder,  as  by  making  a  West- 
ern Union  joint.  Joints  must  then  be  soldered  and  the  whole 
covered  with  an  insulation  equal  to  that  on  the  conductors. 
Approved  splicing  devices  also  acceptable.  (i2-e.) 

85.  What  kind  of  insulation  is  required  for  outside  wir- 
ing up  to  service  connection  for  electric  lighting,  heat  or 
power? 

Both  approved  weather-proof  and  rubber-covered  are 
acceptable.  (i2-a.) 

86.  Where  is  rubber-covered  wire  obligatory  on  pole  line 
services? 

From  first  support  on  building  to  cut-out  or  main 
block  and  service  switch;  and  from  main  block  up  to  a  point 
on  the  outside  of  the  building  where  the  wires  will  be  free 
from  danger  of  contact  with  awnings,  swinging  signs,  or 
building  attachments  or  appurtenances.  (i2-a.) 

87.  How  far  apart  in  order  to  prevent  moisture  must 
service  wires  not  run  in  conduit  be  kept? 

Not  less  than  i  ft.  apart.     (i2-b.) 

88.  How  should  aerial  service  wires  enter  buildings? 
Through  separate  tubes,  such  as  glass  or  porcelain, 

slanting  upward  toward  inside  of  building  for  aerial  work; 
properly  extended  iron  conduit  for  enclosing  wires  of  the 
service  is  approved  on  low  potentials.  (i2-f.) 

29 


30          QUESTIONS  AND  ANSWERS  ON  THE 

Note  No.  13:  A  properly  fitted  iron  conduit  would  have  an 
approved  service  head  which  is  secured  by  any  device  or 
arrangement  whereby  the  service  wires  properly  emerge  through 
a  bushing  or  heading. 

89.  Can  service  wires  be  allowed  to  come  in  contact 
with  trees  or  any  other  substances? 

No.     (i2-b.) 

90.  Where  wires  are  to  be  attached  to  buildings  by 
wooden  blocks,  upon  which  insulators  are  mounted,  how 
must  blocks  be  treated? 

Painted  with  at  least  two  coats  of  water-proof  paint. 

(12-b.) 

91.  How  high  must  outside  wiring  be  run  over  highest 
point  of  flat  roof? 

At  least  7  ft.     (12-0.) 

92.  How  high  must  they  pass  over  ridged  and  pitched 
roofs? 

At  least  i  ft.     (i2-c.) 

93.  What  kind  of  insulators  must  be  used  on  wires  ex- 
posed to  the  weather  for  lighting  or  power? 

Petticoat  insulators  of  glass  or  porcelain;  porcelain 
knobs  or  cleats  or  rubber  hooks  will  not  be  approved.  ( 1 2  -d. ) 

94.  When  outside  wires,  such  as  services,  are  so  sheltered 
that  they  are  not  exposed  to  the  weather,  what  kind  of  in- 
sulators may  be  used? 

If  low  potential  (maximum  550  volts)  glass  or  porce- 
lain knobs  separating  wires  at  least  i"  in.  from  surface 
wired  over  may  be  used  instead  of  petticoat  insulators. 
Wires  must  be  supported  at  least  every  4  1/2  ft.  (i2-d.) 

95.  How  often  must  wires  on  exterior  walls  of  buildings 
for  light,  heat  or  power  be  supported? 

Every  15  ft.  minimum  and  oftener  if  liable  to  dis- 
turbance. (i2-d.) 

96.  Can  electric  light  or  power  wires  be  placed  on  the 
same  cross-arm  with  telephone  or  telegraph  wires? 

NO.       (12-g.) 

97.  What  distance  between  line  wires  is  required  on 
telegraph,  telephone  or  similar  wires  and  electric  light  and 
power  wires  on  the  same  pole? 

The  distance  between  the  two  inside  pins  of  each 
cross  arm  that  carries  an  electric  light  or  power  wire  under 
these  circumstances  must  be  not  less  than  26  in.  (i2-g.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      31 

98.  Define  service  wires  under  the  Code? 

Wires  from  street  lines  to  building  and  into  the  main 
cut-out  and  service  switch.  (i2-a.) 

99.  Where  outside  wires  are  run  in  conduit,  either  from 
an  underground  system  or  combined  with  a  pole  line  sys- 
tem, what  kind  of  wire  is  obligatory  for  service  wires? 

Rubber-covered.     (i2-a.) 
Grounding  in  General.     Read  also  118,  119,  120. 

"Companies  and  Departments  in  charge  of  water  works 
are  urged  to  allow  the  attaching  of  ground  wires  to  their 
piping  systems,  in  the  full  confidence  that  the  integrity  of 
such  piping  systems  will  be  in  no  way  effected,  whatever 
may  be  the  voltage." — National  Fire  Protection  Committee 
recommendation,  March  1912 

Note  No.  14:  Alternating  current  secondary  systems, 
grounds,  as  indicated  by  general  terms  of  questions  on  this 
subject,  involve  considerations  of  life  hazard  to  the  greatest 
extent. 

100.  What  condition  is  imperative  under  fine  print  note 
of  Rule  15  whenever  a  low  potential  (550  volts  or  less)  cir- 
cuit is  grounded. 

That  there  is  no  passage  of  current  over  ground  wire 
under  normal  conditions  of  service.  (Fine  print,  Rule  15.) 

101.  May  neutral  wire  be  grounded  on  direct  current 
three- wire  systems  when  carried  in  underground  work? 

Yes,  if  grounded  at  each  distributing  point  through 
the  box  and  at  the  central  station,  (is-a-2  and  is-a-i.) 

102.  Is  the  ground  connection  with  underground  water 
and  gas  systems  of  the  neutral  wire  on  direct  current  three- 
wire  system  mandatory  under  fine  print  notes? 

Yes,  ground  connection  must  include  all  of  available 
underground  water  and  gas-pipe  system.  (i5-a-i.)  Com- 
mittee's recommendations  for  1913  Code  low  potential  is 
mandatory. 

163.  Is  it  necessary  to  ground  a  direct  current  neutral  on 
a  three- wire  system? 

Code  declares  neutral  wire  may  be  grounded  and  that 
such  grounding  must  be  permanent  and  effective  at  the  cen- 
tral station,  (is-a-i.) 

104.  May  insurance  department  having  jurisdiction  re- 
quire grounding  if  they  deem  it  necessary  on  alternating 
current  secondary  systems,  and  direct  current  neutrals? 


32          QUESTIONS  AND  ANSWERS  ON  THE 

Yes,  under  the  fine  print  notes,  Rule  15  -a,  following 
3;  and  b-3.  Committee  recommendations  for  1913  Code 
make  alternating  mandatory  at  less  than  150  volts  maxi- 
mum ground  difference  between  ground  and  any  point  in 
the  circuit. 

105.  When  two-wire  direct-current  systems  have  no  ac- 
cessible neutral  point,  shall  they  be  grounded? 

No,  under  i5-a-3,  fine  print  note. 

106.  What  kind  and  size  of  wire  is  required  upon  grounds 
in  a  three-  wire  direct-current  system  at  central  stations? 

At  central  stations  copper  no  less  than  neutral  line 
wire  size  and  elsewhere  no  smaller  than  No.  6  B.  &  S. 


107.  What  size  ground  wire  is  required  for  secondaries  of 
alternating  current  systems? 

No  less  than  6  B.  &  S.     (is-d.) 

1  08.  How  often  must  neutral  wire  be  grounded  in  alter- 
nating current  overhead  systems? 

Every  500  ft.     (i5-b-3«) 

109.  On  a  three-phase  system,  how  big  must  the  ground 
wire  be  made? 

Carrying  capacity  equal  to  any  one  of  the  three  mains. 


no.  Where   ground  connection  is  inside   any   ordinary 

building,  or  the  ground  wire  is  inside  of,  or  attached  to,  any 

building,  must  ground  wire  be  of  copper  and  rubber  covered? 

Yes,  Natl.  Electrical  Code  standard.     (Type  letter  R  S 

for  o  to  600  volts.)     (15  -c). 

in.  When  is  protective  covering,  such  as  conduit,  re- 
quired for  ground  wires? 

When  exposed  to  mechanical  injury.     Reference,  fine 
print  note.     (i5-e.) 

112.  What  direction  must  ground  wire  take? 
As  nearly  straight  as  practicable.     (15-6.) 

113.  Can  staples  be  used  for  fastening  ground  wires  on 
building? 

No.     (is-c.) 

114.  Can  ground  wires  be  attached  to  building  or  pole  by 
cleats  or  straps  or  on  porcelain  knobs? 

Yes.     (i5-e.) 

115.  Is  it  necessary  for  ground  connections  for  central 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      33 

stations,    transformer    sub-stations    and    banks    of    trans- 
formers  to    be    made   permanent   and   effective,    and    in- 
clude  the   lead  sheath  of  underground   cables,    as  well  as 
all  available  underground  piping  system? 
Yes.     (i5-f.) 

1 1 6.  Can  individual  transformer  in  building  services  use 
the  water-piping  systems  run  in  the  buildings  for  ground 
connections? 

Yes.     (is-g.) 

Caution. — In  cases  of  connections  for  electric  light,  heat 
or  power  to  ground  upon  water-piping  systems,  a  properly 
made  grounding  should  be  established  on  the  street  side  of 
the  meter.  (i5-g.) 

117.  How  must  ground  wires  be  run  inside  a  building? 
Porcelain  bushings  through  walls  or  partitions;  in 

basements  may  be  supported  on  porcelain  insulators;  other- 
wise run  in  approved  moulding,  or  conduit.     (i5-g.) 

1 1 8.  When  three- wire,  110  volt,  220  volt  or  other  second- 
ary service  wires  are  grounded,  where  must  ground  be  made? 

At  neutral  point,     (is-b-i.) 

119.  Is  the  grounding  on  one  side  of  a  two- wire  secondary 
service  permitted? 

Yes,  provided  the  difference  between  grounding  point 
and  any  other  point  in  the  circuit  will  not  exceed  2^0  volts. 

120.  Is    grounding    of    alternating    current    secondaries 
required? 

Fine  print  note  under  rule  15 -a -3,  declares  ground- 
ing optional  with  insurance  department  having  jurisdiction. 
Wires — Conduited. 

121.  How  must  conduited  services,  etc.,  be  treated? 
Wires  in  conduit  must  in  general   comply  with 

Section  No.  6,  Inside  work,  Code  Class  "C"  for  unlined 
conduits.    (i2-b.)     (Where  applicable.) 

122.  Where  the  situation  or  convenience  requires  the 
service  to  enter  a  cabinet,  is  it  necessary  for  the  conduit  to 
enter  the  cabinet,  as  usual  in  conduit  work? 

Yes.     (28-b.) 

123.  How  must  conduit  work  exposed  to  the  weather  be 
protected? 

Must  be  water -proof.     (i2-b.) 
3 


34          QUESTIONS  AND  ANSWERS  ON  THE 

Note  No.  15:  An  approved  device  or  arrangement  by 
which  water  will  be  kept  from  entering  pipes  meets  this 
requirement. 

High  Tension  (Constant  Potential)  Pole  Lines  —  Over  5000 
Volts. 


Note  No.  16:     The  Code  is  suggestive  rather  than  mandatory 
its  language  on  this  subj 
of  life,  as  well  as  fire  hazard. 


. 

in  its  language  on  this  subject.     It  involves  grave  questions 
,  as  well  a 


The  following  fine  print  note,  appearing  under  Rule  13, 
and  opening  the  subject,  is  explanatory: 

Overhead  lines  of  this  class  unless  properly  arranged  may 
increase  the  fire  loss  from  the  following  causes: 

Accidental  crosses  between  such  lines  and  low-potential  lines 
may  allow  the  high-voltage  current  to  enter  buildings  over  a 
large  section  of  adjoining  country.  Moreover,  such  high- 
voltage  lines,  if  carried  close  to  buildings,  hamper  the  work 
of  firemen  in  case  of  fire  in  the  building.  The  object  of  these 
rules  is  so  to  direct  this  class  of  construction  that  no  increase 
in  fire  hazard  will  result,  while  at  the  same  time  care  has  been 
taken  to  avoid  restrictions  which  would  unreasonably  impede 
progress  in  electrical  development. 

It  is  fully  understood  that  it  is  impossible  to  frame  rules 
which  will  cover  all  conceivable  cases  that  may  arise  in  con- 
struction work  of  such  an  extended  and  varied  nature,  and 
it  is  advised  that  the  Inspection  Department  having  juris- 
diction be  freely  consulted  as  to  any  modification  of  the  rules 
in  particular  cases. 

In  General  on  Over  5000  Volts  Constant  Potential. 

124.  What  precaution  must  be  taken  in  arranging  routes, 
on  5000  volts  constant  potential  pole  lines? 

Avoid  exposure  to  contacts  with  other  electric  cir- 
cuits. (13  -a.) 

125.  Where  lines  come  nearer  to  other  pole  lines,  than  a 
distance  equal  to  the  heighth  of  the  taller  pole  lines;  or 
where  they  must  be  carried  on  same  poles  with  other  wires, 
what  must  be  done? 

Extra  precautions  to  reduce  break  -down  liability  to 
a  minimum,  such  as  use  of  wires  of  ample  mechanical 
strength,  widely  spaced  cross-arms,  short  spans,  double  or 
extra  heavy  cross-arms,  extra  heavy  pins,  insulators  and 
thoroughly  supported  poles. 

The  high  pressure  companies'  own  signalling  wires 
(such  as  telephones)  are  excepted  in  their  own  buildings. 
(13  -b  and  c.) 

126.  When  on  same  poles  with  other  wires,  how  high 
above  them  must  high  tension  be  located? 

At  least  3  ft.     (13-0.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      35 

127.  When  crossing  another  line,  what  pole  construction 
is  required? 

Poles  of  heavy  and  substantial  construction.     (i3-d.) 

128.  Should  end  insulator  guards  be  placed  on  cross- 
arms  of  5000  volt  wires  carried  above  other  lines? 

Yes,  whenever  feasible.     (i3-d.) 

129.  If  high-pressure  lines  cross  below  other  lines,  what 
construction  should  be  followed? 

The  wires  of  the  upper  line  should  be  dead -ended  at 
each  end  of  the  span  to  double -grooved,  or  to  standard  trans- 
position insulators,  and  the  line  completed  by  loops,  (is-d.) 

130.  What  forms  of  construction  are  then  obligatory? 
One  of  the  f  ollowing  three  : 

"i.  The  height  and  length  of  the  cross-over  span  may 
be  made  such  that  the  shortest  distance  between 
the  lower  cross-arms  of  the  upper  line  and  any 
wire  of  the  lower  line  will  be  greater  than  the 
length  of  the  cross -over  span,  so  that  a  wire 
breaking  near  one  of  the  upper  phis  would  not 
be  long  enough  to  reach  any  wire  of  the  lower 
line.  The  high -pressure  wires  should  prefer- 
ably be  above  the  other  wires.  (i3-d-i.) 

"2.  A  joint  pole  may  be  erected  at  the  crossing  point, 
the  high -pressure  wires  being  supported  on  this 
pole  at  least  3  ft.  above  the  other  wires. 
Mechanical  guards  or  supports  must  then  be 
provided,  so  that  in  case  of  the  breaking  of  any 
upper  wire,  it  will  be  impossible  for  it  to  come 
into  contact  with  any  of  the  lower  wires.  (13- 

d-2.) 

"3.  Whenever  neither  of  the  above  methods  is  feasible, 
a  screen  of  wire  should  be  interposed  between 
the  lines  at  the  cross-over.  This  screen  should 
be  supported  on  high  tension  insulators  or 
grounded,  and  should  be  of  such  construction 
and  strength  as  to  prevent  the  upper  wires  from 
coming  into  contact  with  the  lower  ones."  (13- 

d-3-) 

131.  What  kind  of  suspension  wires  are  suggested  for  use 
in   preventing  liability  of   contact   between  high-pressure 
wires  located  on  poles  above  other  wires? 


36          QUESTIONS  AND  ANSWERS  ON  THE 

Same  as  those  employed  for  suspending  aerial  tele- 
phone cables.  They  should  be  supported  on  high -potential 
insulators,  have  ample  strength,  and  be  carried  for  one  strand 
on  each  side  of  the  joint  pole.  Fine  print  of  Rule  13  over 
No.  3. 

132.  When  suspension  wires  are  not  used,  how  should 
guard  wires  be  installed? 

Carried  above  and  below  the  lower  wires  for  one 
span  on  each  side  of  the  joint  pole.  Should  be  so  spread  as  to 
catch  and  hold  a  falling  high-pressure  wire  out  of  contact 
with  lower  wire.  Fine  print,  Rule  13  over  No.  3. 

133.  How  should  guard  wires  be  supported  or  (alterna- 
tively) grounded? 

Supported  on  high -potential  insulators  or  provided 
with  grounding  ample  to  carry  off  any  possible  current  that 
may  be  delivered  by  high-pressure  wires.  Construction  must 
be  such  that  guard  wires  will  not  be  destroyed  by  any  possible 
arcing  at  point  of  contact.  (13  d-2  fine  print  note.) 

134.  When  neither  suspension  nor  guard  wires  are  feas- 
ible, what  other  method  is  advised? 

A  screen  of  wire  interposed  between  lines  at  the 
cross-over;  screen  treated  as  outlined  in  last  two  questions. 
Must  further  be  of  such  construction  and  strength  as  to  pre- 
vent top  wires  from  falling  on  lower  wires.  (13  d-3.) 

135.  How  high  must  5000  volt  lines  or  over  be  carried 
when  near  a  building,  and  how  far  from  same? 

When  within  25  ft.  of  building  at  height  not  less  than 
front  cornice;  this  height  must  be  greater  than  that  of  the 
cornice,  as  wires  approach  building  in  accordance  with  fol- 
lowing self  -explanatory  table. 

"Distance  of  wire  Elevation  of  wire  above 

from  building.  cornice  of  building. 

Feet.  Feet, 

25  0 

20  2 

15  4 

10  6 

5  8 

2  1/2  9 

!'It  is  evident  that  where  the  roof  of  the  building  continues 
nearly  in  line  with  the  walls,  as  in  Mansard  roofs,  the  height 
and  distance  of  the  line  must  be  reckoned  from  some  part  of 
the  roof  instead  of  from  the  cornice."  (13-®-) 

Underground  Conductors. 

136.  Give  the  Code  requirements  for  underground  con- 
ductors. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      37 

"a.  Must  be  protected  against  moisture  and  mechanical 
injury  where  brought  into  a  building,  and  all 
combustible  material  must  be  kept  from  the  im- 
mediate vicinity. 

"b.  Must  not  be  so  arranged  as  to  shunt  the  current 
through  a  building  around  any  catch -box. 

"c.  Where  underground  service  enters  building  through 
tubes,  the  tubes  shall  be  tightly  closed  at  outlets 
with  asphaltum  or  other  non-conductor,  to  pre- 
vent gases  from  entering  the  building  through 
such  channels. 

"d.  No  underground  service  from  a  subway  to  a  build- 
ing shall  supply  more  than  one  building  except 
by  permission  from  the  Inspection  Department 
having  jurisdiction."  (Rule  17.) 


SECTION  FOUR 

SIGNALLING  SYSTEMS 
WIRING  IN  GENERAL,  APPLIANCES  INCLUDED 

Outside  Wires. 

Pole  Lines. 

Wires  in  Cable. 

Wires  supplying  Current  to  Apparatus. 

Protectors  and  Instruments. 

ALL  OTHER  SYSTEMS  EXCEPT  TELEGRAPH 

Instrument  circuits. 

Re -active  coils  and  condensers. 

GROUND  WIRES  IN  GENERAL 

WIRELESS  TELEGRAPH  APPARATUS 

Grounding  wireless  telegraph  apparatus. 


39 


SECTION  FOUR 

ALL  SIGNALLING  SYSTEMS 

Section  Four  includes  signal  systems  in  general.  Wireless 
telegraph  and  its  grounding  are  also  included.  References 
to  questions  are  Code  Class  "E."  Read  150,  96  and  97. 

(Wiring  for  telephone,  telegraph,  district  messenger  and 
call-bell  circuits,  fire  and  burglar  alarms,  and  all  other 
systems  which  are  hazardous  only  because  of  their  liability 
to  become  crossed  with  electric  light,  heat  or  power  circuits.) 

Questions  applying  upon  the  low  potential  110  to  220 
volts  or  higher  wiring  for  the  wireless  telegraph  apparatus 
will  be  found  under  Section  No.  6,  [references  Code  Class 
PC."] 

Other  requirements  for  Generators  are  treated  by  ques- 
tions in  Section  No.  1,  [Code  Class  "A."] 

^^  Where  entire  circuit  is  underground  questions  with  ref- 
erences 85-b  to  m  inclusive  do  not  apply.  Questions  with 
references  85-j  to  p  inclusive  apply  where  apparatus  will  not 
carry  10  amperes  indefinitely. 

^e^Questions  with  references  85-f  to  i  inclusive  apply 
where  apparatus  will  carry  10  amperes  indefinitely. 

WIRING  IN  GENERAL,  APPLIANCES  INCLUDED 

137.  May  two  wires  of  a  system  enter  building  through 
one  tube? 

Yes,   promulgated  in   list   of   approved  Electrical 
Fittings,  April  1912. 

138.  Is  it  obligatory  that  the  wiring  in  a  building  test 
free  from  ground? 

Yes. 

139.  Is  an  all-metallic  circuit  required  for  all  signalling 
systems  except  telegraph? 

Yes.     (85-f.) 

140.  Must  single  pole  cut-outs  designed  for  from  251  to  600 
volts  and  containing  fuses  rating  not  over  10  amperes  be 
provided  for  each  wire  of  a  circuit  at  entrance? 

Yes.     (85-g.) 

41 


42          QUESTIONS  AND  ANSWERS  ON  THE 

141.  What  is  the  smallest  sized  copper  wire  allowed  inside 
of  a  building  on  signalling  system? 

Sixteen,  B.  &  S.     (85 -h.) 

142.  Are  entrance  cut-outs  allowed  in  the  vicinity  of 
easily  ignitable  stuff  or  combustible  surroundings  of  any 
kind? 

No.     (85-g.) 

143.  What  general  questions  apply  to  inside  wiring  for 
these  systems? 

All  on  o  to  600  volts,  Section  6,  Code  Class  "C"  for 
insulation  and  support.  (85 -h.)  See  Question  No.  284 
and  249.  No.  141  modifies. 

Following  applies   to   all   systems   whether   wires   from 
central  office  to  building  are  overhead  or  underground. 

144.  When  the  entire  system  is  inside  of  a  building  and  is 
not  in  the  vicinity  of  light  or  power  wiring  may  staples  be 
used? 

Yes.     (8s-n.) 

Note  No.  17:  All  -these  inside  wires  may  use  staples.  For 
the  safest  and  most  reliable  work  insulated  staples  or 
buttons  are  used. 

145.  How  must  wires  bunched  together  in  a  vertical  run 
within  a  building  be  protected? 

In  non-combustible  flexible  tubing  unless  run  in  a 
fire -proof  shaft  with  fire  stops  at  each  floor.  (85-0.) 

146.  How  may  signal  and  electric  light  and  power  wires 
be  run  in  the  same  shaft,  and  what  special  provision  is 
made? 

One  must  run  in  tubing  or  separated  from  the  other 
at  least  2  in.  (85-0.) 

147.  Can  signal  wires  be  run  in  the  same  tube  with  electric 
light  or  power  wires? 

No.     (85-0.) 

148.  How    must    10    ampere    capacity    instruments    be 
mounted? 

On  non -combustible  and  non -absorptive,  approved 
material.  (85-!.) 

149.  How  far  apart  must  holes  for  bases  carrying  fuses  be 
located  or  counter-sunk? 

To  measure  1/2  in.  space  over  circuit  between  head  of 
screws  and  nearest  live  metal  parts.  (85-!.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      43 

Outside  Wires. 

Outside  wires  should  only  be  run  on  roofs  of  buildings 
by  special  permission  of  Insurance  Department  having 
jurisdiction.  (8s-a.) 

150.  When  are  telephone,  telegraph,  district  messenger 
and  call-bell  circuits  and  fire  and  burglar  alarms  subject  to 
regulation  at  all  under  the  National  Electrical  Code? 

Whenever  electric  light,  heat  or  power  circuits  are 
in  the  vicinity.     (Rule  85,  first  italics.) 

151.  Can  outside  wires  be  placed  on  the  same  cross  arm 
with  electric  light  or  power  wires? 

No.     (85-a.) 

152.  Should  outside  wires  in  signalling  systems  of  any 
kind  be  permitted  in  the  same  duct,  man-hole,  or  hand-hole 
or  conduit  systems  with  electric  light  or  power  wires? 

No.     (85 -a.) 

153.  Do  single  man-holes  or  hand-holes  separated  into 
sections  by  means  of  partitions  of  brick  or  tile  meet  require- 
ments of  152? 

Yes.     (8s-a.) 
Pole  Lines. 

154.  Give  distance  required  between  two  inside  pins  of 
each   cross-arm   where   attached   to   pole   bearing  electric 
light  or  power  wires? 

Minimum  24  hi.     Code  recommends  signal  wires  be 
placed  on  lower  cross-arms  beneath  such  wires.     (85-0.) 

155.  What  kind  of  insulation  is  required  for  wires  attached 
to  wooden  buildings  and  parts  of  buildings? 

Rubber -covered  unless  cabled.     (85  -c.) 

156.  Are  iron  wires  permitted  to  enter  a  building  from  pole 
line? 

No.     (85-d.) 

157.  What  kind  of  wire  is  required  from  pole  lines  to 
enter  a  building,  and  quote  requirements? 

Approved  rubber -covered  copper  from  last  outside 
supports  or  protectors  (type  letter  R.  S.  is  approved);  drip 
loops;  entrance  through  porcelain  or  approved  tubes  slanting 
upward  from  outside.     (85-c-d-e.) 
Wires  in  Cable. 

158.  What  special  exceptions  are  made  for  all  wires  in 
cable? 


44          QUESTIONS  AND  ANSWERS  ON  THE 


Need  not  be  rubber-covered  copper;  and  need  not 
meet  other  requirements  of  previous  Question.     (85,  second 
italics.) 
Wires  Supplying  Current  to  Apparatus. 

159.  How  must  such  wires  be  insulated  and  supported? 
According  to  Question  284  dnd  Section  6  or  National 

Code  requirements  for  Class   "C"  for  inside  wiring  0-600 
volts.     (85 -h.) 

1 60.  Must  porcelain  supports  be  so  arranged  from  entrance 
of  building  to  the  protector  that  no  contact  will  be  made  at 
any  point  up  to  the  instrument? 

Yes.     (8s-k.) 
Protectors  and  Instruments. 

161.  What  does  the  term  "protector"  include? 

Fuses  :  current  to  ground  shifting  devices  (lightning 
arrester,)  magnetic  cutouts  and  heat  coils.  (85-m-i.) 

162.  What  kind  of  cut-out  and  fuse  must  be  installed  on 
a  telegraph  system  circuit  to  protect  each  wire? 

Two  thousand  volts  potential  approved  single  pole 
cut-outs  containing  fuses  not  exceeding  i  ampere. 
(85-m-i.) 

163.  When  10  amperes,  251  to  600  volt  fuses  are  installed 
in  main  entrance  on  telegraph  systems,  may  the  2000  volt 
1  ampere  fuses  be  placed  between  switchboard  and  instru- 
ment? 

Yes;  and  instrument  located  as  near  switchboard  as 
possible.  (85-m-i.) 

ALL  OTHER  SYSTEMS,  EXCEPT  TELEGRAPH 

Instrument  Circuits. 

164.  How  must  instruments  be  mounted? 

So  that  all  live  parts  will  be  thoroughly  insulated 
from  wall  on  which  protector  is  attached;  and  be  properly 
mounted  on  non-combustible  approved  supports.  (85-m-i.) 

165.  Is  a  500  volt  maximum  lightning  arrester  required  for 
protection? 

Yes.  (85-m-2.) 

1 66.  How  must  its  grounding  be  arranged? 

So  that  chance  of  accidental  grounding  is  minimum. 
(8s-m-2.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      45 

167.  What  fuse  protection  is  required  in  protectors? 
Fuse  to  open  circuit  properly  in  case  of  cross  with 

light  or  power  wires.     (85-01-2.) 

Note  No.  18:  Fuses  should  be  provided  to  comply  with 
requirements  as  indicated  in  Section  Six,  Division  3,  Question 
No.  478,  or  under  Code  Class  "C"  for  whatever  voltage 
threatens  or  is  in  vicinity  of  protector. 

Code  ad  vises  heat  coils  necessary  in  all  circuits  normally 
closed  through  magnet  winding  that  cannot  indefinitely 
carry  at  least  5  amperes  current.  (See  85-01-2.)  A  heat 
coil  or  sufficiently  sensitive  instrument  which  will  operate 
before  a  sneak  current  can  damage,  the  instrument  pro- 
tector is  guarding  should  also  be  included  in  protection. 
(85-m-2.) 

168.  How  must  fuses  be  placed? 

Protecting  arrester  and  heat  coils.     (85-01-3.) 

169.  Is   it   required  that  protector  terminals  be  marked 
"line,"  "instrument"  and  "ground"?     Are  abbreviations 
acceptable? 

Yes.     (8s-m-3.) 

Reactive  Coils  and  Condensers. 

170.  How  must  reactive  coils  be  constructed  and  installed 
and  treated? 

As  sources  of  heat  and  mounted  on  non-combustible, 
approved  material.  (80 -a.) 

171.  How  must  condensers  be  treated? 

Like  other  apparatus  operating  with  equivalent  volt- 
age and  current;  must  have  non -combustible  cases  and  sup- 
ports; be  isolated  from  combustibles  and  treated  as  sources 
of  heat.  (8o-b.) 

GROUND  WIRES  IN  GENERAL 

172.  What  is  the  smallest  size  and  kind  of  ground  wire 
for  protective  devices  permitted? 

Eighteen  B.  &  S.  rubber -covered  for  from  o  to  600 
volts;  with  preservative  compound  permissibly  omitted  for 
from  o  to  600  volts.  (85-!-!  and  2.) 

173.  How  must  ground  wires  be  run? 

Straight  as  possible  to  good  permanent  ground;  con- 
nection to  ground  device  shall  be  made  as  near  as  possible 


46          QUESTIONS  AND  ANSWERS  ON  THE 

to  earth;  water  or  gas  pipes  are  acceptable  grounds,  connec- 
tion in  latter  cases  must  be  made  between  meter  and  street 
main.  (85-1-3.) 

174.  Where  obtainable,  is  it  required  that  preference  be 
given  to  water  pipes  over  gas  pipes? 

Yes.     (85-1-3.) 

175.  Where  a  ground  rod  driven  in  the  earth  is  used,  how 
must  grbund  wire  be  attached? 

By  an  approved  ground  clamp  fastened  to  a  thor- 
oughly clean  surface  on  rod  or  pipe;  or  pipe  thoroughly 
cleaned  and  tinned  with  resin  flux  solder;  ground  wire 
tightly  wrapped  around  and  thoroughly  soldered  thereto. 

(85-1-30 

176.  May  steam  or  hot- water  pipes  be  used  for  a  protector 
ground? 

No.     (85-1-3.) 

WIRELESS  TELEGRAPH  APPARATUS 

Following   questions   apply   to  wireless  telegraph  appa- 
ratus, except  where  installed  on  shipboard. 

177.  Of  what  kind  of  wire  must  aerial  conductors  be 
made? 

No  limitations  specified  by  the  Code. 

178.  What  must  be  done  in  order  to  protect  system  from 
high-potential  surges? 

Transformer  inserted  having  a  ratio  giving  550  volts 
maximum  or  less  or  two  condensers  in  series  across  line; 
connection  between  condensers  permanently  and  effectively 
grounded.  Condenser  capacity  should  not  be  less  than 
i  hah*  micro  farad.  (86 -e.) 
Grounding  Wireless  Telegraph  Apparatus. 

179.  What  is  smallest  size  of  conductors  that  may  be 
used  for  a  permanent  ground? 

Four  B.  &  S.     (86-a.) 

1 80.  How  should  ground  be  made? 

By  copper  plate  buried  in  ground  connection  or  with 
usual  copper  wire  hi  direct  line  to  water  pipe  street  side  of 
connections.  (86-c.) 

181.  Is  it  necessary  that  grounds  upon  aerial  conductors 
are  cut  off  from  all  apparatus  within  the  building? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      47 

Yes.     (86-b.) 

182.  Give  another  method  of  acceptable  grounding  for 
aerial  conductors? 

Short  gap  lightning  arrester  may  be  inserted  in  ground 
wire  circuit.  Gap  on  this  arrester  to  be  not  over  .015  in. 
between  brass  or  copper  plates;  plates  not  less  than  21/2 
in.  parallel  to  the  gap,  by  11/2  in.  and  with  thickness  not 
less  than  1/8  in.;  whole  mounted  on  non-combustible,  ap- 
proved insulating  materials.  (86-c.) 

183.  Wherever  aerial  conductor  is  grounded  to  water 
pipes  or  other  satisfactory  earthing,  what  size  switch  must 
be  employed  joining  aerial  to  the  ground  connection? 

Not  less  than  standard  100  ampere  knife  switch. 
(86-d.) 


SECTION  FIVE 

ARC  LAMPS  IN  GENERAL 

Multiple  Incandescent  Arcs 

CONSTANT  CURRENT  SYSTEMS 

(Principally  Series  Arcs) 
Incandescent  Lamps  in  Series. 


49 


SECTION  FIVE 

ARC  LAMPS  IN  GENERAL 

Following  questions  apply  to  all  kinds  of  arc  lamps,  ex- 
cept as  specifically  indicated  otherwise,  as  in  Question  No.  195. 

References  principally  from  Code  Class  "C,"  Constant 
Potential. 

184.  Are  stops  to  prevent  carbons  from  falling  out  in 
case  clamps  get  loose  required? 

Yes.     (74-a.) 

185.  Is  it  necessary  to  insulate  exposed  parts? 
Yes.     (74-b.) 

1 86.  How  must  arc  light  terminals  be  designed? 

So  supply  wire  contact  is  not  loosened  by  lamp  mo- 
tion during  trimming.     (74-d.) 

187.  Is  it  necessary  for  spark  arresters  to  close  the  top 
hole  of  the  globe  from  the  escape  of  carbon  flakes? 

Yes.     (75-a.) 

188.  Is  a  cut-out  necessary  for  each  individual  lamp;  or 
each  series  of  lamps? 

Yes.     (33-a.) 

189.  What  size  is  required  for  branch  conductors  for  arc 
lamps? 

Fifty  per  cent,  excess  normal  current  required  for 
each  lamp.     (33-a.) 

190.  Must  resistances  and  regulators  for  arc  lamps  be  en- 
closed in  non-combustible  material? 

Yes.     (33-b.) 

191.  Can  incandescent  lamps  be  used  as  resistances? 
No.     (33-b.) 

192.  Are  spark  arresters  required  for  arc  lamps  when  in 
vicinity  of  inflammable  materials? 

Yes.    [33 -c.] 

193.  Is  wire  netting  required  around  globe  of  series  arc 
lamp  in  vicinity  of  inflammable  material? 

Yes.     (33 -c  and  2i-c.) 

194.  How  far  above  sidewalk  must  outside  arcs  be  hung? 
Eight  ft.     (33-c.) 

195.  How  must  inside  arc  lamps  be  installed? 

51 


52          QUESTIONS  AND  ANSWERS  ON  THE 

Out  of  reach  or  protected  from  mechanical  injury; 
when  arranged  for  lowering  and  raising,  if  conductors  are 
larger  than  14  B.  &  S.  shall  be  stranded.     (33-d.) 
Multiple  Incandescent  Arcs. 

196.  Are  multiple  or  incandescent  arcs  (generally  fed  by 
ordinary  incandescent  circuits)  subject  to  the  requirements 
for  series  arc  lamp  spark  arresters? 

No,  where  they  have  tight  inner  globe.     (21-0.) 

CONSTANT  CURRENT  SYSTEMS 

Principally  Series  Arcs. 

Following  questions  apply  upon  constant-current  sys- 
tems unless  otherwise  specified  or  indicated.  References 
principally  taken  from  Code  Class  "C"  (Inside  Work), 
Constant  Current  Systems.  Questions  under  Wiring  in 
general,  as  applicable,  Section  No.  6,  Code  Class  "C"  also 
apply. 

Wire  Table  1  for  sizes  of  wire,  Section  No.  9,  Reference 
Code  Class  "C,"  Rule  18,  also  governs. 

197.  What  kind  of  wire  must  be  used  for  series  arcs  on 
the  inside  of  building? 

Rubber-covered.     (20 -a.) 

198.  What  kind  of  series  arcs  entrance  or  service  switch 
must  be  used,  and  how  installed? 

Double  contact  mounted  on  non-combustible  base; 
free  from  moisture;  and  convenient  of  access  for  police  or 
fireman.  (20 -b.) 

199.  May  wires  for  series  arcs  be  concealed  or  encased? 
No,  unless  by  requirement  of  Inspection  Department 

having  jurisdiction.     (20 -c.) 

200.  How  far  apart  must  series  arc  light  wires  and  cir- 
cuits be  run  except  at  points  where  they  enter  their  appli- 
ances, such  as  lamps,  cut-outs,  etc.? 

Eight  inches.     (20 -d.) 

201.  Must  arc  light  wires  on  side  wall  and  other  wires 
subject  to  mechanical  injury  be  protected? 

Yes,  see  Question  No.  279,  Section  6,  Methods  (20 -e) 
equally  applicable. 

202.  Must   series  arc  lamps  be  kept  isolated  from  in- 
flammable materials? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      53 

Yes.     (2 1 -a.) 

203.  Are  broken,  cracked,  or  insecurely  fastened  globes 
acceptable? 

No.     (2i-b.) 

204.  Is  a  wire  netting  around  a  series  arc  globe  and 
approved  spark  arrester  required? 

Yes  (2i-c.) 

205.  What  is  the  largest  size  mesh  allowed  in  arc-lamp 
wire  netting;  is  netting  obligatory? 

One  and  one-fourth  inches.;  yes.  (21-0.)  Excep- 
tion :  "Enclosed  Arc"  lamps  with  tight  globes.  (21 -c.) 

206.  Where   exposed   to    flyings    of    easily   inflammable 
materials,  what  substitution  for  spark  arrester  is  required? 

Carbons  completely  enclosed  in  tight  globes.     (2i-c.) 

207.  How  must  arc  lamps  not  hung  from  hanger  boards 
be  supported? 

Insulating  supports  other  than  their  conductors 
must  be  used.  (2i-d.) 

208.  How  must  switches  on  constant-current  devices, 
such  as  series  arc  lights,  operate? 

Automatically  close  main  circuit  and  disconnect 
branch  wires  or  branch  arc  when  turned  off.  (65  -b.) 

209.  Are   both   hand   and   automatic   shunted   switches 
required  for  constant-current  systems? 

Yes.     (74-c.) 

210.  How  must  hanger  boards  be  built? 

"a.  Hanger -boards  must  be  so  constructed  that  all 
wires  and  current-carrying  devices  thereon  will  be  exposed 
to  view  and  thoroughly  insulated  by  being  mounted  on  a  non- 
combustible,  non-absorptive,  insulating  substance.  All 
switches  attached  to  the  same  must  be  so  constructed  that 
they  shall  be  automatic  in  their  action,  cutting  off  both  poles 
to  the  lamp,  not  stopping  between  points  when  started  and 
preventing  an  arc  between  points  under  all  circumstances." 
(73-a.) 

211.  May  series  lamps  be  attached  to  gas  fixtures? 
No.     (46 -b,  also  22 -d.) 

Incandescent  Lamps  in  Series.     Christmas  minatures  ex- 
cepted,     See  Decorative  Lighting. 

212.  Must  automatic  cut-out  be  provided  for  each  lamp 
in  a  series  circuit? 

Yes.     (22-a.) 


54      OFFICIAL  NATIONAL  ELECTRICAL  CODE 

213.  How  must  incandescent  lamps  in  series  circuits  be 
suspended? 

From  a  hanger  board  by  rigid  tube.     (22-b.) 

214.  Are    multiple    series    or    series    multiple    systems 
approved? 

No.     (22-0  and  46-a.) 

2 15.  May  incandescent  lamps  in  series  circuits  be  attached 
to  gas  fixtures? 

No.     (22-d.) 


SECTION  SIX 

(INSIDE  WORK) 

Light,  Power  and  Heat.  For  Signalling  Systems,  see  Section 
Four.  (Code  Class  "E.") 

Section  Six  includes  installation  questions  upon  all  classes 
of  inside  work.  References  principally  from.  Code  Class 
"C"  (Inside  Work)  and  Code  Class  "D"  (Fittings,  Mate- 
rials and  Details  of  Construction,  for  all  systems  and  volt- 
ages). 

For  tables  and  information  on  material  and  fittings,  see 
Section  Nine. 

Wiring  in  General. 


55 


SECTION  SIX 

WIRING  IN  GENERAL 

Question  84,  reference  15-c,  applies. 

216.  What  is  the  wire  table  giving  allowable  carrying 
capacity  for  rubber-covered  wire  and  other  insulation? 

See  Table  No.  i,  Section  9. 

217.  What  type  letter  applies  for  National  Code  standard 
plain  rubber-covered,  low-potential  (up  to  550  volts  with 
maximum  allowance  of  605  for  motors)  conductors? 

Type  letter  R.  S.     See  also  Table  No.  5. 

218.  How  much  must  the  complete  covering  slow  burn- 
ing wires  measure? 

In  accordance  with  Tables  Nos.  2  and  3,  Section  9. 

219.  Where  is  underwriter's  wire  (type  letters  S-B)  par- 
ticularly acceptable? 

In  hot  dry  places,  as  back  of  a  large  switchboard  or 
wire  tower.  (5 2 -a,  fine  print  note.) 

220.  What   is  the  safe  carrying  capacity  for  insulated 
aluminum  wire? 

Eighty-four  per  cent,  of  that  given  in  the  tables  for 
copper  wire  with  the  same  kind  of  insulation.  (i8-a.)  (See 
Table  No.  i,  Section  9.) 

221.  How  close  must  stranded  conductors  be  computed? 
In  stranded  conductors,  the  sum  of  the  circular  mills 

of  the  individual  wires  must  not  be  less  than  the  total  circu- 
lar mills  of  the  conductor  size  required  by  more  than  11/2 
per  cent.  (49-a.) 

222.  Is  it  necessary  in  applying  a  stranded  conductor  to 
use  all  strands  under  the  clamp? 

To  within  11/2  per  cent,  of  the  actual  circular  mills 
required  for  the  proper  size  of  wire.  (49-a.)  Read  455. 

223.  What  is  the  smallest  size  of  wire  allowed  for  interior 
wiring,  fixture  wire  not  included? 

No.  14  B.  &  S.     (i6-a.) 
57 


58          QUESTIONS  AND  ANSWERS  ON  THE 

224.  Does  the  Code  allow  larger  amperage  on  weather- 
proof and  slow-burning  wires  than  on  rubber-covered? 

Yes.     See  Table  No.  i,  Section  9. 

225.  Is  a  concession  given  for  alternating  current  motor 
wiring  under  this  table? 

Yes,  see  Table  No.  i-B,  Section  9. 

226.  Can  primary  wires  of  over  3500  volts  (extra  high 
potential  system)  be  brought  into  or  over  any  buildings  ex- 
cept power  stations  and  sub-stations? 

No.     (47  -a.);    applies  also  outside  work,  Section  3. 

227.  How  must  secondary  wires,  whose  immediate  pri- 
maries are  over  3500  volts,  be  installed,  and  is  there  any 
exception? 

Must  be  treated  as  extra  high  potential.  Exception 
made  whenever  primary  wires  are  installed  entirely  under- 
ground in  city,  town  or  village  limits  ;  or  in  accordance  with 
questions  on  over  5000  volts,  Constant  Potential,  Section  3, 
Code  Class  "B."  U8-a.) 

228.  Is  tape  on  type  letter  R.S.L.  lead-covered  cable  or 
wire  acceptable  instead  of  a  braid? 

Yes,  if  it  increases  diameter  over  insulating  wall  as 
much  as  1/64  in.  (5o-j.) 

229.  On  0  to  600  volt  multiple  conductors,  is  thickness 
of  lead  same  as  required  for  a  single  conductor,  acceptable? 

Yes,  in  sizes  of  bunch  conductors,  the  same  diameter. 
(5o-j.) 

230.  What  is  the  maximum  wattage  allowed  in  house 
and  similar  wiring  for  one  fused  branch  circuit,  two  wires? 

Six  hundred  and  sixty  watts.  Not  applicable  to 
grounded  circuits  of  street  railways  systems.  [23-d.] 

231.  How  should  wires  be  bushed  through  brick  walls? 
By  non  -combustible,  non  -absorptive,  insulative  tubes, 

continuous  through  holes.  Water  -proofed  iron  pipes  or  con- 
duits bushing  hole  as  a  container  for  short  length  tubes  thus 
affording  continuity  of  protection  for  wires  is  acceptable. 


232.  Are  holes  and  open  spaces  at  outlets  allowed,  such 
as  caused  by  broken  plastering? 

No.     (26-u  and  28-d.) 

233.  Where  change  in  size  of  wire  is  made,  as  at  a  branch 
circuit,  is  a  cut-out  with  proper  fuse  required? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      59 

Yes,  unless  cut-out  fuse  already  in  larger  wire  will 
protect  smaller.  (23 -b.) 

Note  No.   19:     Fuses  must  protect  wires  as  the  first  con- 
sideration and  be  guaged  accordingly. 

234.  What  does  the  term  "nearest  accessible  place"  as 
applied  to  the  required  location  of  main  cut-outs  mean? 

Nearest  practical  point  for  the  cut-outs  to  be  located 
for  fusing  or  attention,  and  the  nearest  practical  point  for 
the  service  wires  to  enter  the  building.  In  underground 
service  this  would  often  be  within  easy  hand  reach  from 
floor.  In  overhead,  conditions  might  justify  approval  where 
the  aid  of  an  ordinary  step  ladder  is  needed. 

For  an  unprotected  fuse  block  a  range  of  from  6  to 
12  ft.  from  floor  is  customarily  permitted,  and  selected. 

235.  What    does   the   term    "nearest   readily   accessible 
place"   mean  as  required  for  the  location  of  all  service 
switches? 

Nearest  practical  place  where  switch  can  be  located 
within  about  5  ft.  from  floor,  or  within  quick  hand  reach. 
A  residence  second  story  is  an  approved  location. 

236.  What  is  meant  by  the  term  "readily  accessible"  in 
the  requirement  that  armored  cable  and  other  grounding 
connections  for  metallic  protective  systems  must  be  exposed 
to  view  or  readily  accessible? 

Must  be  easily,  but  not  necessarily  quickly  reached. 
A  connection  in  an  ordinary  house  cellar  to  an  exposed  water 
pipe  is  an  example. 

237.  When  may  fuses  be  omitted  in  the  neutral  of  three- 
wire   direct-current   or  single-phase  systems,   at  the  main 
block? 

When  the  neutral  is  properly  grounded  on  the 
outside.  (23-b.)  Read  Section  3,  Grounding  in  general. 

238.  When  fuses  are  omitted  in  the  neutral  of  inside  wiring 
(grounded  services  outside)  at  the  main  block,  may  they  be 
omitted  in  all  the  two- wire  house  circuits  taken  off  the  three- 
wire  house  mains? 

No.     (23-d.) 

239.  May  three- wire  circuits  be  continued  or  tapped  from 
a  grounded  (outside)  system  of  house  mains  for  use  as  lamp 
circuits,  when  neutral  is  solid? 

No.     (23-d.) 


60          QUESTIONS  AND  ANSWERS  ON  THE 

240.  What  kind  of  circuits  are  required  for  lamps,   or 
other  660  watt  house  circuits,  when  taken  off  grounded 
(services  outside)  three- wire  house  mains? 

Two-wire  (if  fuses  are  omitted  in  neutral).     (23-d.) 

241.  When  a  non-grounded,  three-wire  system  is  used,  oi 
less  than  250  volts  between  outside  wires,  for  house  wiring, 
may  three-wire  circuits  be  taken  off  the  house  mains  for; 
supplying  lamps? 

Yes,  but  limitation  of  660  watts  still  applies  for  each 
side  of  such  circuit.     (23-d.) 

242.  May  tungsten  lamps,  carbon  lamps,  and  fan  motors 
be  used  on  the  same  house  circuit  of  not  exceeding  250  volts? 

Yes,  provided  the  limit  of  660  watts  is  not  exceeded. 
(23-d.) 

243.  May  an  electric  meter  be  installed  before  a  main 
switch  or  fuse? 

No.     (24-a.) 

244.  When  voltage  is  over  250  between  two  outside  wires 
of  a  system,  how  must  both  wires  of  a  branch  or  tap  lamp 
circuit  be  protected? 

By  proper  fuses.     (23-d.) 

245.  If  fuses  are  provided  for  three-wire  circuits  at  the 
juncture  with  three- wire  fused  house  mains  on  a  grounded 
neutral  (outside)  system;  and  electric  lamps  or  other  houst 
circuit  appliances  are  attached  to  it  to  a  maximum  of  66( 
watts,  total,  does  this  comply  with  Code? 

Yes,  if  maximum  voltage  between  outside  wires  ij 
not  over  250  volts.     (23-d.) 

246.  May  circuits  be  three-wire  from  either  a  groundec 
neutral   (outside)   or  a  non-grounded  neutral  where  ove: 
250  volts  is  used  between  the  two  outside  wires? 

No.     (23-d.) 

Note  No.  20:  Distinguishing  terms:  A  house  main  has  n 
current-consuming  device,  such  as  a  lamp,  attached,  j 
circuit  is  attached  to  a  main,  and  is  usually,  but  not  neces 
sarily,  a  smaller  wire,  and  directly  supplies  the  lamps,  sma 
motors,  etc. 

247.  In  dry  places,  when  it  is  impossible  or  impractlca 
to  place  the  whole  of  a  circuit  on  the  insulating  supports 
what  construction  must  be  followed? 

Metal  Conduit  or  approved  armored  cable.     (26 
and  t.)     Read  302. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      61 

248.  What  is  the  limit  for  fuses  in  branch  cut-outs,  and 
what  exception  is  made? 

55  volts  or  less  12  amperes 

Over    55  but  less  than  125  volts      6  amperes 
125  to  250  volts  3  amperes 

(23-d.) 

Exception:  Small  motors  grouped  under  single  set  fuses 
are  allowed  6  amperes,  voltage  not  over  250. 

Limited  to  1320  watts  per  circurt  load.     (39-h  and 
83-g.)     Read  615  and  620. 


SECTION  SIX 

DIVISION  ONE 

KNOB  AND  TUBE  WORK— ALL  KINDS 

Protection  of  Wires  from  Mechanical  Injury. 
Exposed  Knob  and  Tube  Work. 
Knob  and  Tube  Work  Concealed. 
Non-metallic  Flexible  Tubing. 
Wooden  Moulding  Work. 


63 


DIVISION  ONE 

Treating  of  knob  and  tube  work  of  all  kinds ;  knob  work 
open;  knob  work  concealed.  Also  of  non-metallic  flexible 
tubing,  and  wooden  moulding. 

Following  questions  unless  specifically  designated  by  head- 
ing or  otherwise,  apply  in  general  on  low  potential  10  to  550 
volts.  Motors  allowed  10  per  cent,  or  605  volts,  at  gener- 
ator or  transformer. 

Questions  with  References  16  to  19  inclusive  apply  all 
systems  and  voltages.  Constant-current  system  questions 
are  under  Section  No.  5.  Both  knob  and  tube  work  ex- 
posed and  knob  and  tube  work  concealed  rely  on  air-gap 
insulation  in  addition  to  the  wire  insulation  (except  at 
supports  and  unavoidable  contacts  where  porcelain  tubes 
are  generally  used).  Correctly  installed  in  suitable  places 
they  have  proven  safe  and  durable.  Unlike  the  metallic 
protective  systems,  this  class  of  work  never  has  the  cover- 
ings over  the  wires  grounded.  In  this  it  is  a  non-grounded 
system. 

KNOB  AND  TUBE  WORK— ALL  KINDS      - 

Note  No.  21:  Knob  and  tube  work  in  so-called  open  or 
exposed  wiring,  and  concealed  knob  and  tube  work  all  rely 
upon  air-gap  insulation  for  durability  and  protection  against 
grounding,  except  at  the  supports,  usually  of  porcelain.  This 
system  seldom  deteriorates.  Grounds  are  required  on  inside 
work  of  this  kind  only  where  a  regular  conduit  system 
appears,  making  a  "mixed"  job. 

Following  apply  to  both  open  and  concealed  knob  and 
tube  work,  and  are  principally  installation  questions.  Ref- 
erences Code  Class  "C"  (Inside  Work)  and  Code  Class  "D" 
(Fittings) . 

249.  How  far  apart  and  how  far  from  surface  wired  over 
must  wires  be  kept  in? 

5  65 


66          QUESTIONS  AND  ANSWERS  ON  THE 


1.  Open  work,  dry  places. 

2.  Open  work  damp  places. 

3.  Concealed  work. 

In  accordance  with  the  following : 


Distance 

Distance 

Distance 

Code    I 

Voltage 

from 

between 

between 

rule  and! 

surface 

wires 

supports 

section  1 

Open  work 

0-300 

V 

2| 

*f 

26-h.    1 

dry  places 

301-550 

\" 

4" 

44' 

26-h.     1 

1 

Open  work 

0-300 

V 

w 

44' 

26-j.   j 

damp  places 

I 

301-550 

I" 

4" 

4*' 

26-j.    1 

Concealed 

work 

0-300 

1" 

5" 

41" 

26-r.    I 
1 

Distance  between  supports  to  be  shortened  for  rigid 
support  if  necessary.  (26-h  and  r). 

Fine  print  note  advises  this  rule  will  not  be  interpreted 
to  forbid  placing  of  neutrals  of  three -wire  systems  in  the 
center  of  a  three -wire  cleat  where  difference  between  out- 
side wires  is  not  over  300  volts,  and  that  the  outside  wires  are 
separated  2  1/2  in.  (62-6.)  See  also  No.  284. 

Knobs  must  always  hold  wire  i"  from  surface.     (64-6.) 

250.  Are  wires  run  near  water  tank  or  pipe  considered 
subject  to  moisture? 

Yes.     (26-f.) 

251.  Can  wires  be  run  on  knobs  or  upper  edges  of  joist 
in  unfinished  attics? 

No.     (26-f.) 

252.  How  must  conduit  or  cable  be  installed  on  a  mi: 
knob  and  tube  and  cable  or  conduit  job? 

Just  as  for  a  complete  and  continuous  conduit  53 
properly  begun  and  terminated.     (26-t.) 

Note  No.  22:  A  mixed  knob  and  tube  job  where  condt 
must  be  grounded  should  not  be  confused  with  a  mere  protectu 
from  mechanical  injury  where  the  protection  need  not  tx 
grounded. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      67 

253.  How  must  wires  be  kept  away  from  contact  with 
gas  or  water  pipes? 

By  permanent  separation,  with  continuous  and  firmly 
fixed  non-conductor  where  crossing,  such  as  porcelain  tube 
fixed  at  both  ends  with  friction  tape  to  wire ;  or  by  approved 
device  for  same.  (i6-e.) 

254.  What  insulation  must  be  used  inside  of  buildings  on 
wire  subject  to  action  of  corrosive  vapors? 

Either  rubber-covered  or  weather-proof.     (26-1.) 

255.  What  insulation  should  be  used  for  wires  subject  to 
unusual  heat? 

Slow -burning.     (52 -a,  fine  print  note.) 

256.  Under  what  conditions  may  slow-burning  wire  be  ^ 
used  inside  of  buildings  under  ordinary  circumstances? 

When  not  subject  to  moisture  and  run  open  in  cleats 
and  knobs.  (26-g.) 

257.  Must  stranded  wires  be  soldered? 

Yes,  except  in  flexible  cords,  must  be  soldered  before 
being  fastened  under  clamps  and  binding  screws  and  terminal 
lugs.  (i6-c.)  Exception:  Where  approved  solderless  ter- 
minal connection  is  used. 

258.  Is  it  obligatory  to  keep  wires  from  contact  with 
walls,  floors  or  timbers? 

Yes.     (i6-d  and  26-r.) 

259.  In  wet  places,  is  an  air  space  between  wires  and 
pipes  in  both  concealed  and  open  work  obligatory? 


r 


260.  How  must  conductors  be  run  to  avoid  contact  with 
pipes  they  may  cross  in  both  concealed  and  open  work? 

It  is  recommended  over  rather  than  under  pipes  sub- 
ject to  moisture.     (i6-f.) 

261.  Are  approved  bushings  or  flexible  non-metallic  tub- 
ing necessary  over  wires  entering  cabinet  and  how  must 
they  be  installed? 

Yes,  they  must  tightly  fit  entrance  holes  hi  cabinets 
and  be  well  secured  in  place.     (26-a.) 

262.  Must  wires  in  entering  completely  fill  up  entrance 
holes  in  bushings? 

Yes.     (26-a.) 

263.  How  must  wires  in  general  be  mounted? 


68          QUESTIONS  AND  ANSWERS  ON  THE 

Non-combustible,  non-absorptive  insulators,  such  as 
glass  or  porcelain.     (i6-b.) 

264.  How  must  porcelain  cleats  grip  the  wires? 
Firmly  without  injury  to  the  covering.     (62 -a.) 

265.  What  kind  of  split  knob  or  single  wire  cleats  are 
required  for  wire  larger  than  No.  4  ? 

Must  have  two  supporting  screw  holes.     (64-b.) 

266.  Can  solid  knobs  be  used  on  wire  sizes  smaller  than 
No.  8? 

No.     Exception  per  283.     (i6-b.) 

267.  Are  solid  knobs  of  proper  size  allowed  for  support  of 
wires  No.  8  or  larger? 

Yes.     (i6-b.) 

268.  What  kind  of  tie  wires  are  required? 

Must  have  insulation  equal  to  the  wires  they  fasten. 
(i6-b.) 

269.  Are  nails  fitted  with  leather  heads  or  proper  washers 
allowed  for  split  or  wire  gripping  knobs  or  cleats? 

Yes.     (i6-b.) 

270.  How  long  must  a  nail  for  a  knob  or  cleat  be  made? 
Must  project  into  the  wood  work  not  less  than  hah* 

length  of  the  knob;  and  fully  thickness  of  a  cleat.     (i6-b.) 

271.  How  much  surface  separation  must  at  all  times  be 
maintained  between  screws  or  nails  for  knobs  and  the  con- 
ductors? 

At  least  1/4  in.     (64-b.) 

272.  Is  it  obligatory  that  solid  knobs  be  smooth  grooved 
for  containing  a  wire? 

Yes.     (64-a.) 

273.  Can  wires  for  electric  light,  heat  or  power  for  con- 
cealed or  open  work  be  fastened  or  attached  by  staples? 

No.     (26-b.) 

274.  How  must  approved  split  knobs  be  made? 

In  two  pieces,  viz.  :  a  base  and  a  cap  arranged  to  hold 
wire  firmly  in  place  without  injury  to  covering.     (64-a.) 
Protection  of  Wires  from  Mechanical  Injury. 

275.  Is  it  obligatory  to  protect  wires  where  subject  to 
mechanical  injury? 

Yes.     (26-e.) 

276.  What    kinds   of   protection   are   approved    for   the 
installation  of  electric  conductors  in  elevator  shafts? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE     69 

Approved  lined  or  unlined  metal  conduits,  flexible 
metallic  conduits  or  armored  cables,  all  properly  installed. 
(i6-g.) 

277.  In  crossing  floor  timbers  in  cellars  or  in  similar 
conditions,  how  must  open  work  wires  be  installed? 

Attached  by  insulating  supports,  such  as  glass  or 
porcelain,  to  underside  of  a  wooden  strip  not  less  than  1/2  in. 
thick  and  3  in.  in  width;  or  guard  strips  each  side  of  and 
close  to  wire  are  acceptable  if  strips  are  at  least  7/8  in. 
thick  and  as  high  as  the  insulator  they  protect  from  mechan- 
ical injury.  (26-6.) 

278.  Is  it  obligatory  for  all  side-wall  protection  to  extend 
5  ft.  above  the  floor? 

Yes.  (26-6.)  In  metal  moulding  systems  in  resi- 
dences, offices,  and  similar  locations,  this  is  sometimes 
reduced  by  consent,  to  3  in.  above  floor.  (2p-b.) 

Note  No.  23:  Npn-metallic  flexible  tubing  or  metal 
moulding  is  not  applicable  as  a  sufficient  protector  of  wires 
from  mechanical  injury.  (26-6  and  2Q-b.) 

Protection  Against  Mechanical  Injury. 

279.  Describe  approved  methods  of  protecting  exposed 
work  on  side  walls  from  mechanical  injury. 

Method  No.  i:  Box  wires  leaving  an  air  space  of  I 
in.  around  the  conductors,  boxing  closed  at  the  top;  wires 
come  through  bushed  holes.  (26-6.)  Suggestion :  Bushing 
should  be  rigid. 

Method  No.  2  :  Install  metal  unlined  conduit  or  pipe, 
reinforcing  insulation  of  each  of  the  circuit  wires  with  an 
approved  flexible  tubing  extending  continuously  from  first 
support  below  to  first  support  above  the  conduit  or  pipe. 
(26-e.) 

Method  No.  3 :  Continuous  single  lined  metal  con- 
duit terminated  with  a  lined  and  bushed  conduit  box  at  each 
end.  Continue  ordinary  circuit  wires  through  the  conduit. 
No  extra  braided  wire  is  required.  (26-6.) 

Method  No.  4  :  Same  as  No.  3,  using  unlined  conduit 
and  boxes  and  the  extra  braided  conduit  wire,  type  R-D  (see 
Section  9)  within  the  conduit  system ;  if  circuit  wires  are  of 
the  ordinary  open  work  type  R-S,  make  a  tap  in  the  box 
from  the  ordinary  wires  to  the  extra  braided  conduit  wires. 
(26-6,  -28)  (e  and  f  excepted)  also  apply  here. 


70          QUESTIONS  AND  ANSWERS  ON  THE 

Note  No.  24:  Approved  fittings  may  be  used  instead  of  boxes; 
They  should  have  ample  room  for  joints.  Flexible  steel  conduit 
may  be  used  instead  of  rigid  conduit  or  pipe,  in  Methods  2  and  4. 

280.  Is  it  necessary  to  ground  short  section  of  iron  pipe 
or  conduit  used  in  side-wall  protection? 

No.     (28-f.) 

281.  Can  twin  wires  be  used  in  knob  and  tube  work, 
either  concealed  or  open? 

No,  use  of  twin  wires  is  limited  to  conduit  work  or 
where  flexible  conductors  are  necessary.     (26-d.) 
Exposed  Knob  and  Tube  Work. 

Following  questions  apply  to  so-called  "open  knob  and 
cleat  work"  exposed  to  view. 

282.  What  kind  of  insulations  must  be  used? 
Approved  rubber;    slow -burning  weather-proof,   or 

slow-burning  insulation,  i.e.,  type  letters  R-S,  S.  B.  W.,  and 
S.-B.     (26-g.) 

283.  How  must  wires  at  ends  of  runs  be  supported? 

By  solid  porcelain  or  glass  knobs;  or  strain  insu- 
lators. (i6-b.) 

284.  How  far  from  surface  wired  over  and  how  far  apart 
must  porcelain  or  other  supports  keep  the  wires  in  dry  places? 

In  accordance  with  the  following : 

Voltage  Distance  from       Distance  between   Distance    apart 

surface  wires 

0  to  300  1/2  in.  2  1/2  in.  4  1/2  ft. 

301  to  550  1  in.  4  in. 

(26-h) 

Read  249. 

285.  When  wires  are  liable  to  disturbance,  what  must  be 
done  to  secure  rigid  support  under  all  conditions? 

Wires  must  be  supported  oftener  than  the  required 
41/2  ft.,  and  as  frequently  as  necessary  to  secure  results. 
(26-h.) 

286.  In  buildings  of  mill  construction,  when  mains  are 
not  less  than  No.  8  B.  &  S.  and  are  not  liable  to  disturbance, 
how  far  apart  can  they  be  run  and  what  special  privilege 
is  given? 

May  be  separated  about  6  in.;  run  from  timber  to 
timber,  and  be  supported  at  each  timber  only;  not  breaking 
around.  (26-h.) 

287.  How  close  must  the  last  support  of  a  line  be  placed 
to  the  final  socket  rosette  or  similar  outlet? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      71 

Twelve  inches     (26-h.) 

288.  What  is  the  distance  required  between  electric  light 
and  bell  and  signal  wires  running  parallel? 

Not  less  than  2  in.  unless  separated  by  a  firmly  fixed 
non-conductor  continuous  and  creating  a  permanent  separa- 
tion. Insulation  on  the  wire  is  not  acceptable  as  a  sufficient 
compliance  with  this  rule.  (i6-e.)  Applies  all  systems  and 
voltages.  Inside  work. 

Knob  and  Tube  Work  Concealed. 

Following  questions  apply  to  so-called  concealed  knob 
and  tube  work,  300  volts  maximum. 

289.  Will  flexible  tubing  over  wires  be  accepted  instead  of 
bushings  where  wires  enter  a  cabinet? 

Yes,  if  extending  from  last  porcelain  support  into  the 
cabinet.  (26-a.). 

290.  Can  wires  be  laid  in  plaster,  cement  or  similar  finish? 
No.     (26-b.) 

291.  Can  wires  be  fished  in  concealed  work  or  otherwise 
any  great  distance? 

No.     (26-0.) 

292.  What  special  provision  is  made  for  the  fishing  of 
wires? 

Only  permitted  where  conditions  are  such  that  in- 
spector having  jurisdiction  can  satisfy  himself  of  its  necessity 
and  that  rules  have  been  complied  with.  (26-c.) 

293.  What  kind  of  insulation  is  required  for  concealed 
knob  and  tube  work? 

Approved  rubber-covered.     (26-q.) 

294.  How  must  wires  be  run  for  concealed  knob  and  tube 
work? 

On  non  -  combustible,  non  -  absorptive  insulators. 
(26-r.)  Exception  per  292,  247  and  302. 

295.  How  far  apart  must  wires  be  kept? 
Five  niches  minimum.     (26-r.) 

296.  How  far  from  surface  wired  over  must  concealed 
work  insulators  keep  the  wires? 

One  inch.     (26-r.) 

297.  Are  wires  separated  by  timbers  or  studding  and  run 
singly  approved? 

Yes.     (26-r.) 


72          QUESTIONS  AND  ANSWERS  ON  THE 

298.  Must  separation  from  walls,  floors,  timbers  and  other 
woodwork  in  the  building  be  preserved? 

Yes.     (26-r.) 

299.  How  must  wires  passing  through  cross  timbers  of; 
plastered  partition  in  concealed  work  be  protected? 

By  additional  tube  extending  at  least  4  in.  above  tim- 
ber. (26-r.) 

300.  In  concealed  work,  how  must  outlet  box  or  plate  be 
installed? 

Flushed  with  finished  surface.     (28-d.) 
Non-metallic  Flexible  Tubing. 

Note  No.  25:     Non-metallic  flexible  tubing  is  applied  as  an 
extra  protective  covering  rather  than  a  conduit. 

301.  Where  must  flexible  tubing  be  used  in  concealed 
knob  and  tube  work? 

Must  be  used  at  points  where  wires  come  together, 
such  as  knob  and  tube  outlets,  and  at  distributing  centers 
when  5  in.  separation  cannot  be  maintained.  (26-r.) 

302.  May  continuous  lengths  of  flexible  tubing  be  used  as 
a  part  of  a  concealed  knob  and  tube  system  where  wires  are 
to  be  fished? 

Yes,  when  the  wires  cannot  be  placed  on  porcelain 
supports  or  knobs  without  damage  (as  in  old  buildings) ;  lim- 
ited to  300  volts ;  must  not  be  exposed  to  moisture.  (26-5.) 

303.  In  dry  places,  is  flexible  non-metallic  tubing  ap- 
proved for  fishwork  in  a  concealed  knob  and  tube  system? 

Yes,  on  maximum  300  volts  if  impracticable  to  use 
the  insulating  supports.  (26-5.) 

304.  How  far  must  flexible  tubing  project  at  combina- 
tion fixture  outlets? 

Flush  with  outer  end  of  gas  cap.     (26-u.) 

305.  How  must  flexible  tubing  be  marked? 

With  distinctive  manufacturer's  marking  entire 
length  of  tube.  (63-!.) 

306.  Are  tubings  whose  lining  is  removable  in  continuous 
lengths  of  over  3  ft.  approved? 

No.     (63-d.) 

307.  Is  a  moisture-proof  compound  necessary  for  the  out- 
side cover  of  a  flexible  tubing? 

Yes.     (63 -e.) 

308.  When  kinked  or  flattened  or  straightened  out,  is  a 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      73 

flexible   tubing,    which  closes  sufficiently  to  prevent  inser- 
tion of  the  wire,  approved? 
No.     (63-h.) 

309.  How  tough  and  tenacious  must  tubing  be  made? 
To  withstand  severe  tension  without  injury.     (63  -g.) 

Wooden  Moulding  Work.     Limited  to  300  volts  or  less. 

310.  Can  any  ordinary  approved   rubber-covered   wire, 
Type  R.  S.,  suitable  for  knob  and  tube  work,  be  used  in 
wooden  moulding? 

Yes.     (26-k.) 

311.  Are  joints  in  wires  or  taps  from  wire  to  wire  direct 
allowed  on  wires  in  moulding  of  any  kind? 

No,  approved  devices,  such  as  "moulding  branch 
blocks"  must  be  used  for  taps  or  branching  connections. 

(26-k.) 

312.  Is  there  any  limitation  on  the  number  of  circuits  to 
wooden  moulding? 

None  given  by  Code. 

313.  May  wooden  moulding  be  used  in  damp  or  concealed 
places? 

No.     (26-k.) 

314.  When  may  wooden  moulding  be  used? 

Only  in  exposed  dry  places  where  difference  of 
potential  between  any  two  wires  on  same  moulding  is  not 
over  300  volts.  (26-!.) 

315.  Is  the  painting  of  wooden  moulding  with  two  coats 
of  water-proof  material  obligatory? 

Yes,  unless  soaked  with  a  moisture  repellant.     (6o-a.) 

316.  Is   it  necessary  for  moulding   to  be  made  in  two 
pieces? 

Yes;  backing  and  capping.     (60 -b.) 

317.  Can  soft  wood  be  used  for  moulding? 
Code  suggests  hard  wood  only.     (60 -b.) 

318.  Is  it  required  that  wooden  mouldings  be  marked  with 
manufacturer's  name  and  marking? 

No,  specifically  required  for  metal,  but  no  require- 
ment for  wood. 

319.  On  alternating  current  systems,  must  two  wires  of 
a  circuit  be  drawn  in  the  same  wooden  moulding  channel? 

Not  required  by  the  Code.  Customarily  in  the 
separate  grooves. 


74     OFFICIAL  NATIONAL  ELECTRICAL  CODE 

320.  What  must  be  the  thickness  of: 

First,  back? 

Second,  sides? 

Third,  tongue  between  conductors? 

First,  3/8  in.  from  the  bottom  of  groove  through 
the  backing. 

Second,  1/4  in.  through  side  from  groove. 

Third,  tongue  thickness  1/2  in.  between  conduc- 
tors. (60 -b.) 


SECTION  SIX 

DIVISION  TWO 

METALLIC  PROTECTIVE  SYSTEMS 
IN  GENERAL 

Interior  Conduits — All  Kinds. 
Lined  Metal  Conduits. 
Metal  Conduits — Unlined. 
Metal  Conduits — Flexible. 
Armored  Cables 
Armored  Cables — Grounding. 

METAL  MOULDINGS 
[Limited  to  300  Volts,  660  Watts] 
Metal  Moulding.     Grounding. 


75 


SECTION  SIX 
DIVISION  TWO 

Metallic  Protective  Systems,  under  which  is  grouped: 
conduits  of  all  kinds;  lined  metal  conduits;  unlined  metal 
conduits;  flexible  metal  conduits;  armored  conductors; 
metal  moulding. 

METALLIC  PROTECTIVE  SYSTEMS 

Note  No.  26:  The  author  has  grouped  rigid  and  flexible 
metallic  conduit;  armored  flexible  conductor;  and  metal 
moulding  under  the  metallic  protective  systems.  Metallic 
protective  systems  offer  the  fullest  measure  of  protection  from 
mechanical  injury  to  interior  wires.  In  conduits,  properly 
installed,  conductors  may  be  withdrawn  and  insertea  at  will. 
For  metal  moulding,  accessibility  to  the  wires  is  secured. 
Armored  flexible  conductors  are  quickly  installed.  In  a  few 
cases,  iron  piping  is  accepted  under  the  Code  for  protective 
purposes  as  well  as  conduit,  but  iron  piping,  even  galvanized, 
is  not  encouraged,  nor  much  used  except  for  outside  work. 

For  work  exposed  to  view,  all  of  the  metallic  protective 
systems  are  accepted.  For  concealed  work  or  in  damp  places, 
or  exposed  to  mechanical  injury  all  except  metal  moulding  are 
approved. 

All  these  systems  require  grounding.  They  rely  upon 
contact  insulation,  of  the  conductors  contained,  for  durability 
instead  of  the  air  gap  of  the  knob  and  tube  system. 

Wherever  metallic  protective  systems  are  combined  with 
knob  and  tube  systems,  care  should  be  taken  that  the  former 
is  definitely  begun  and  terminated  in  a  proper  manner,  by  a 
correct  box  or  fitting. 


IN  GENERAL 

321.  What  requirements  are  applicable  to  all  of  the  metal- 
lic protective  system? 

Must  be  continuous  from  outlet  to  outlet,  to  junction 
boxes  or  approved  fittings  (for  metal  mouldings  especially 
designed);  must  at  all  outlets  be  provided  with  approved 
terminal  fittings  protecting  insulation  of  conductors  from 
abrasion,  unless  such  protection  is  afforded  by  the  construc- 
tion of  the  boxes  or  fitting;  and  wires  must  be  continuous  in- 
side tubing  without  splice  or  cap.  (2Q-a,  27-6  and  26-0.) 
All  alternating-current  conductors  of  circuit  must  be  placed 
in  the  same  casing  or  conduit.  (26-6,  29-6  and  26-p.) 

77 


?o  i. 

Tk  i 
)•) 


78          QUESTIONS  AND  ANSWERS  ON  THE 

322.  May  wires  of  different  circuits  of  the  same  system! 
be  placed  in  the  same  metal  or  wooden  moulding  channel?  jj 

No  rulings  specifically  forbid  it  if  channels  can  prop- 
erly accommodate  the  wires. 

Note  No.  27:     The  Code's  intention  is  to  limit  mouldings  f] 
a  separation  of  opposite  polarity  wires. 

Wires  of  the  same  system  and  polarity  may  therefore  go  ^ 
the  same  channel.  The  number  of  circuits  in  conduit  work 
li  mi  ted,  however,  to  four  2- wire  or  three  3- wire.  (See  26-p. 

Interior  Conduits — All  Kinds. 

Questions  on  grounding  Nos.  373-378  apply. 

323.  When  may  more  than  four  2- wire  or  three  3-wil 
circuits  be  placed  in  any  one  conduit? 

Special  permission  of  insurance  department  having 
jurisdiction.     (26-p.) 

324.  May  conduits  under  any  circumstances  contain  cifl 
cuits  of  different  systems? 

No.     (26-p.) 

325.  What  is  the  smallest  internal  diameter  allowed  fa 
conduit? 

Five-eighths  inch,  inside  measurement.     (28-a.) 

326.  May  conductors  be  installed  in  conduits  before  co 
pleting  the  entire  conduit  system? 

No.     (28-c.) 

327.  May  wires  be  drawn  in  conduit  before  carpenterii 
or  other  mechanical  work  on  building  is  completed? 

No.     (26-0.) 

328.  Is  mechanical  security  of  a  conduit  system  by  mea 
of  twisted  wires  or  clips  or  otherwise  securing  conduit 
position  required? 

Yes,  (28-b)  also  applies  armored  cables.     (27-b.) 

329.  Must  unlined  conduit  have  an  interior  coating? 
Yes.     Code  says  "Which  will  readily  distinguish 

from  ordinary  commercial  pipe  commonly  used  for  other  tha 
electrical  purposes."     (58-!.) 

330.  Is  it  required  that  conduit  be  properly  entered  an 
be  secured  to  all  fittings? 

Yes.     (28-b.) 

331.  In  service  connections  and  main  runs,  must  ea« 
conduit  run  continuously  into  the  main  cut-out  cabinets  <! 
the  gutter  surrounding  the  panel  board,  as  the  case  may  be 

Yes.     (28-b.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      79 

332.  Is  it  necessary  to  equip  each  outlet  with  an  approved 
outlet  box  and  are  there  any  exceptions? 

Yes;  but  where  wires  pass  from  conduit  system  to 
another  without  a  splice,  joint  or  tap,  an  approved  fitting 
with  separately  bushed  holes  for  each  conductor  is  acceptable 
instead  of  box.  (28-d  and  5Q-c.) 

333.  May  terminal  fittings  of  this  character  be  used  on 
combination  or  straight  electric  fixture  outlets? 

No.     (28-d.) 

Note  No.  28:  Interpreted  to  apply  to  concealed  work  only. 
Fixtures  may  be  fed  on  exposed  work  from  a  properly  approved 
and  installed  fitting. 

334.  Is  it  necessary  to  support  conductors  in  conduits  in 
vertical  conduit  risers? 

Yes. 

"Conductors  in  vertical  conduit  risers  must  be  sup- 
ported within  the  conduit  system  in  accordance  with  the 
following  table : 

No.  14  to  o  every  zoo  ft. 

No.  oo  to  oooo  every  80  ft. 

oooo  to  350,000  C.  M.  every  60  ft. 

350,000  C.  M.  to  500,000  C.  M.  every  50  ft. 

500,000  C.  M.  to  750,000  C.  M.  every  40  ft. 

750,000  C.  M.  every  35  ft."     (26-0.) 

335.  How  much  of  a  turn  in  the  conduit  is  considered 
satisfactory  support? 

Ninety  degrees.     (26-0-1.) 

336.  May  a  switch  box  or  any  kind  of  a  box  occupied  by 
a  fitting  or  device  be  used  as  a  junction  box,  or  place  for 

lalf  taps,  splices,  etc.? 

No  specific  rule  forbidding,  but  practice  is  bad. 

337.  Do  approved  insulating  supports  within  properly 
covered  junction  boxes,  inserted  at  intervals  in  vertical  runs 

atisfy  requirements  for  supporting  cables  in  conduit? 

Yes,  if  insulating  supports  are  fastened  so  as  to  bear 
he  weight  of  conductors;  boxes  must  have  proper  covers. 
26-0-2.) 

338.  Are  cables  supported  in  approved  junction  boxes  by 
wo    insulating   supports    so    placed    that    conductors    are 
leflected  not  less  than  90  degrees,  and  carried  a  distance  of 
wice  the  diameter  of  the  cable,  approved? 


80          QUESTIONS  AND  ANSWERS  ON  THE 

Yes,  this  method  is  satisfactory.  Additional  security 
by  tying  cable  to  insulators  in  boxes  is  also  approved.  (26- 

0-3.) 

339.  What  is  the  greatest  number  of  bends  allowed  in  a 
run  of  conduit? 

Four  one -quarter  bends  from  outlet  to  outlet,  or 
cabinet  to  outlet;  bend  at  outlet  not  being  counted.  (28-h.) 

340.  How  must  elbows  of  bends  be  made? 

So  that  conduit  or  lining  of  same  will  not  be  injured. 

(28-h.) 

341.  What  is  the  shortest  curve  allowed  for  conduits? 
Three  and  one-half  inches.     (28-h.) 

342.  Is  it  necessary  that  approved  bushings  or  fastening 
plates  be  used  upon  metal  conduits  where  they  enter  junc- 
tion  boxes,   and  at  all   other  outlets,   and  is   there  any 
exception? 

Yes;  exception  made  when  protection  is  obtained  by 
use  of  approved  nipples  properly  fitted,  making  bushings  or 
fastening  plates  unnecessary.  (28-6.) 

343.  When  may  outlet  plates  be  used? 

Only  when  impracticable  to  use  boxes.     (27-b.) 

344.  Where  a  conduit  system  connects  to  exposed  wiring, 
must  different  kinds  of  conductors  be  insulated  from  each 
other  at  end  of  the  conduit  by  fitting,  bushing  or  box? 

Yes.     (59  -c.) 

345.  How  must  boxes  be  made  for  use  of  combination 
fixture  outlets? 

So  that  gas  pipe  may  be  properly  connected  to  box. 
(59-e.) 

346.  Must  combination  gas-electric  outlets  be  arranged 
to  secure  the  conduit  or  flexible  tubing  in  place? 

Yes,  or  approved  fastening  device  is  acceptable. 
(59-e,  and  fine  print  note.) 

347.  Is  the  threaded  end  of  an  exposed  conduit  system 
approved  for  fastening  and  support  of  a  threaded  conduit 
box? 

Yes.     (59-g.) 

348.  Is  it  necessary  for  switch  and  outlet  boxes  to  be 
fastened   independently   of  the  support  given  by  threaded 
conduit  in  concealed  work? 

Yes.     (59-gO 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      81 

349.  Is  it  necessary  for  switch  boxes  to  entirely  enclose 
the  switch  on  sides  and  back? 

Yes.     (59-h.) 

350.  Can  retaining  screws  for  box  be  used  for  securing 
switch  in  position? 

No.     (59-h.) 

351.  What  kind  of  covers  are  acceptable  for  outlet  boxes? 
Metal   lined  with   insulated  material   permanently 

secured  to  metal,  at  least  1/32  in.  in  thickness;  or,  of 
porcelain  or  other  approved  material  of  such  form  and 
thickness  as  to  afford  suitable  protection  and  strength;  or  if 
metal,  must  have  thickness  equal  to  the  box  walls.  (5Q-i.) 

352.  Is  porcelain  satisfactory  for  lined  conduits,  switch 
and  junction  boxes  all  systems? 

Yes.     (5Q-i.)     Boxes  can  be  used  on  all  systems. 

353.  Where  underground  services  enter  building  through 
tubes,  is  it  necessary  to  seal  ends  with  asphaltum  or  other 
non-conductor? 

Yes.     (i7-c.) 

354.  Can  subway  services  supply  more  than  one  building? 
No,  except  by  special  permission  from  department 

having  jurisdiction.     (i7-d.) 

355.  Is  ordinary  brass  conduit  or  paper  tubing  acceptable 
for  any  kind  of  a  light,  heat  or  power  circuit? 

No.     (58-j.) 

Lined  Metal  Conduits. 

356.  What  are  the  required  specifications  for  lined  metal 
conduit? 

First,  metal  covering  must  be  as  strong  as  require- 
ments for  unlined  conduits.  Second,  must  not  be  seriously 
affected  by  burning  out  of  the  wire  inside  the  tube  when  its 
metal  is  connected  to  one  side  of  the  circuit.  Third,  must 
have  the  insulating  lining  firmly  secured  to  the  pipe.  Fourth, 
lining  must  not  soften  injuriously  at  any  temperature  below 
212°  F.  And  insulating  lining  must  be  at  least  1/32  in. 
in  thickness.  Rule  58,  "b,"-"c,"-"d,"-"e,"-"f"  and  "g." 

357.  Is  it  necessary  for  boxes  for  lined  conduit  to  have 
an  insulating  lining? 

Yes,  must  have  a  tough  and  tenacious  insulating  lin- 
ing at  least  1/32  in. -firmly  secured  in  position.     (59-f.) 
6 


82          QUESTIONS  AND  ANSWERS  ON  THE 

Metal  Conduits — Unlined. 

358.  Can  ordinary  galvanized  iron  or  plain  iron  pipe  be 
used  as  a  conduit? 

No.     (58-1.) 

Metal  Conduits — Flexible. 

359.  What  are  the  general  requirements  of  flexible  met 
lie  conduits? 

Must  offer  the  same  protection  hi  practice  as  is  offered 
by  rigid  unlined  conduits.  (58  -n.) 

360.  What  is  required  where  metallic  flexible  conduits 
are  installed? 

Radius  of  the  curve  at  any  point  must  not  be  such  as 
to  interfere  with  the  withdrawal  of  the  wires  contained  in- 
side (58-n.) ;  also  must  be  continuous  from  outlet  to  outlet 
and  junction  box  to  junction  box.  (See  58-m.) 

361.  When  flexible  metal  conduit  or  armored  cable  is 
used  for  fish  work  on  a  concealed  knob  and  tube  job,  is) 
grounding  required? 

Yes,  all  sections,  either  separately  or  through  one 
ground,  after  bonding  all  together.  (28-f.) 

Armored  Cables. 

362.  How  must  armored  cables  in  general  be  installed? 
Practically  same  requirements  as  ulterior  conduits. 

363.  What  is  required  thickness  of  armored  cable? 
Must  be  strong  enough  to  turn  away  a  nail;  and 

afford  ample  protection  against  mechanical  injury  to  the 
wires  or  conductors  it  encloses.     (57 -a.) 

364.  May  runs  of  armored  cables  be  spliced? 
No.     (27-a.)     In  boxes  excepted. 

365.  In  completed  buildings,  may  both  outlet  boxes  and 
outlet  plates  be  omitted? 

Yes,  where  conditions  are  such,  that  insurance  de- 
partment having  jurisdiction  approves  and  cable  is  firm  and 
rigid  hi  place.  (27 -b.) 

366.  What  thickness  of  lead  covering  is  demanded  by 
1911  Code  on  armored  cable  in  damp  places? 

One  -thirty  -second  inch  hi  thickness.     (27-d.) 

367.  What  is  the  smallest  radius  allowed  in  bends 
armored  cable? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      83 

One  and  one -half  inches.     (27  -h.) 

368.  Is  the  lead  covering  required  on  armored  cable  when 
installed  on  brick  walls  or  ordinary  plaster  walls? 

No,  unless  permanently  damp;  hi  breweries  and 
stables  and  exposed  to  the  weather  it  is  required.  (27-d.) 

369.  May  box  bushings  be  omitted  from  armored  cables 
at  outlet  and  when? 

Approved  terminal  fittings  must  be  used  to  protect 
conductors  from  abrasion  hi  all  cases  unless  the  junction  or 
outlet  box  is  specially  designed  for  use  with  cable.  (27-6.) 

370.  Must  the  junction  boxes  for  armored  cable  always 
be  accessible? 

Yes.     (27-f.) 

371.  Where  is  armored  cable  required  to  have  a  lead  cov- 
ering between  the  armor  and  the  insulation? 

When  installed  in  fire -proof  buildings  in  course  of 
construction,  and  otherwise  per  question  No  368.  (27-d.). 

372.  Is  a  separate  braid  or  satisfactorily  taped  exterior 
over  all  conductors  together  necessary  in  armored  cables? 

Yes.     (57-b.) 

Armored  Cables — Grounding. 

373.  How  must  armor  of  cable  be  grounded? 
Permanently   and  effectively  to   a   proper   ground; 

gas  pipes  or  water  pipes.  Especially  provided  that  h*  gas 
pipes  are  used,  connections  must  be  on  street  side  of  meter. 
(27-c.) 

Note  No.  29:     Grounding  in  gas  piping  should  in  all  cases 
be  made  as  above.     Water  piping  is  a  more  satisfactory  choice. 

374.  How  must  several  sections  of  armored  cable,  such 
as  circuits  from  a  cabinet,  or  mixed  systems,  be  treated  in 
reference  to  grounding? 

Bonded  together  and  grounded  or  separately  grounded. 

(27-C.) 

375.  Must  ground  wires  be  protected  from  mechanical 
injury? 

Yes.     (27-c.) 

376.  How  must  connections  to  ground  pipe  and  armored 
cable  be  always  treated? 

Must  be  made  by  means  of  approved  ground  clamps; 
with  soldered  wires;  must  be  exposed  to  view  or  readily 
accessible.  (27  -c.) 


84          QUESTIONS  AND  ANSWERS  ON  THE 

377.  What  are  the  minimum  sizes  of  permissible  ground 
wire? 

Where  largest  wire  in  cable  is  greater  than  No.  o 
B.  &  S.,  minimum  size  is  No.  4  B.  &  S.  Where  largest  wire 
in  cable  is  less  than  No.  o  B.  &  S.,  the  minimum  size  is  No. 
10  B.  &  S.  (27-c.) 

378.  Is  good  contact  required  at  outlets  by  the  armor 
of  cables  with  the  outlet  boxes,  junction  boxes  and  cabinets?  • 

Yes.     (27-c.) 

METAL  MOULDINGS 
Limited  to  300  Volts,  660  Watts  (26 -k). 

379.  What  is  the  rule  for  side-wall  protection  in   metal 
moulding  installation  where  the  moulding  is  run  down  the 
side  of  the  wall,  and  how  is  this  modified  in  residences? 

Must  be  run  in  an  iron  pipe  or  unlined  conduit  or 
otherwise  as  in  Division  i,  Question  No.  279.  The  extension 
must  be  made  from  ceiling  below  to  point  5  ft.  above  floor. 
A  concession  to  appearances  is  made  in  residences  and  similar 
places  under  approval  of  authorities  by  which  this  protection 
may  be  run  from  ceiling  below  to  a  point  not  less  than 
3  in.  above  floor.  (29  -b.) 

380.  How  must  all  fittings  of  metal  moulding  be  con- 
structed? 

So  that  a  race-way  continuity  is  effected  and  that 
sharp  metal  corners  or  burrs  will  not  be  present,  especially 
on  the  interior.  (60 -f.) 

381.  Is  any  special  precaution  necessary  at  metal  mould- 
ing outlets? 

Yes,  conductors  must  not  come  in  contact  with 
metal  at  point  where  they  emerge.  (6o-f.) 

Note  30:  Proper  fittings  or  tightly  placed  rubber  bushings  can 
be  used  to  secure  this  result. 

382.  Is  it  necessary  for  the  heads  of  screws  or  bolt  fasten- 
ings on  inside  of  backing  of  metal  moulding  to  come  flush 
with  the  metal? 

Yes.     (6o-g.) 

383.  Must  metal  moulding  be  installed  as  exposed  race- 
ways opened  by  removal  of  capping  or  cover  only? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      85 

Yes.     (60 -h.) 

384.  Can  metal  mouldings  be  used  for  concealed  work? 
No.     (6o-h.) 

385.  Are    screws    or    bolts    required    in    fastening    the 
backing  and  must  the  heads  be  flush  with  the  metal? 

Yes.     (2Q-c.) 

Metal  Moulding — Grounding. 

386.  What  is  the  smallest  size  and  kind  of  grounded  wire 
allowed  for  metal  moulding? 

No.  10  B.  &  S.  copper.     (2g-d.) 

387.  Is  it  required  that  metal  moulding  connections  for 
grounds  be  exposed  to  view;  or,  readily  accessible? 

Yes.     (2Q-d.) 

388.  Are   approved   ground   clamps  required   on   metal 
moulding  at  pipes  or  ground,  as  the  case  may  be? 

Yes.     (2Q-d.) 

389.  Is  grounding  obligatory  to  water  piping,  gas  piping, 
or  correct  ground,  and  must  connections  be  made  on  street 
side  of  gas  system  from  meter? 

Yes.     (2Q_-d.) 


SECTION  SIX 

DIVISION  THREE 
Regulators,  Resistance  Boxes,  Rheostats,  Auto  Starters. 

IN  GENERAL 

Overload  Release  Auto  Starters. 
Switches,  All  Kinds,  Circuit-breakers  and  Cut-outs. 

FUSES,  ALL  KINDS,  AND   ROSETTES 
CABINETS  AND   PANEL   BOARDS— ALL  KINDS 


87 


SECTION  SIX 

DIVISION  THREE 

Questions  under  this  division  apply  to  low  potential,  550 
to  10  volts,  with  an  allowance  of  10  per  cent,  or  605  volts 
at  transformer  or  generator  where  motors  are  used  unless 
otherwise  indicated. 
Regulators,  Resistance  Boxes,  Rheostats,  Auto  Starters. 

390.  Of  what  material  must  rheostats,  resistance  boxes  and 
equalizers  be  made? 

Entirely  of  non -combustible  material,  except  minor 
parts,  such  as  handles,  magnet  insulation,  etc.  All  segments, 
lever  arms,  etc.  must  be  mounted  on  non -combustible  non- 
bsorptive,  insulating  materials.  (78-a.) 

391.  What  kind  of  material  must  be  used  for  resistance 
box  and  equalizer  parts  base  when  not  mounted  on  switch- 
board or  at  least  a  foot  away  from  combustible  materials? 

Slate,  soapstone  or  marble  or  equal.  (4-a.)  Applies 
equally  transformers  (stationary).  (36-c.) 

392.  Is  it  necessary  to  countersink  and  fill  over  bolts  sup- 
porting rheostats,  and  how  much? 

Yes,  1/8  in.  below  surface  and  filled  to  level  with  wax 
or  other  accepted  material.  (4-a.) 

393.  Give  minimum  thickness  of  slab  recommended. 
Not  less  than  1/2  in.     (4-a.) 

394.  How  must  slab  base  of  rheostat  be  secured  in  posi- 
tion? 

Independently  of  the  rheostat  support.  (4-a.)  Ap- 
plies as  well  to  resistances  and  transformers  under  Question 
No.  76.  [Rule  36-c.] 

Note  No.  31:  Statements  about  rheostats  and  all  forms 
of  resistances  practically  apply  wherever  used  to  govern  or 
control  in  the  same  way. 

395.  When  are  dust-proof  face  plates  required? 

On  resistance  devices  liable  to  accumulation  of  dust 
or  combustible  flyings,  such  as  lint.  (4-a.) 

396.  What  is  the  maximum  difference  of  potential  per- 
mitted between  any  two  connecting  wires  on  large  field  or 
similar  resistance  grouping  separate  contact  plates? 

89 


90          QUESTIONS  AND  ANSWERS  ON  THE 

Seventy-five  volts.     (4-0.) 

397.  What  kind  of  wires  are  required  between  resistances 
and  contact  plate  of  rheostat? 

Slow-burning.     (4-0.) 

398.  May  incandescent  lamps  be  used  in  connection  with 
automatic  rheostat  as  protective  resistances,  and  under  what 
provision  and  regulation? 

Yes,  if  they  do  not  act  as  regulating  resistances  of  the 
device;  are  in  porcelain  receptacles  mounted  on  non-com- 
bustible materials;  have  name  plates  with  candle-power  and 
voltage  of  their  current;  and  conditions  must  be  such  that 
they  cannot  be  subjected  to  higher  voltage  than  their  rating. 
(4-b.) 

399.  Is  it  compulsory  for  direct  current  motor  starting 
rheostat  to  be  provided  with  a  no- voltage  release? 

Yes.     (78-f.) 

400.  How  must  protective  and  controlling  device  used  in 
motor  installation  be  located? 

In  plain  sight  of  the  motor  protected  or  controlled; 
otherwise  by  special  permission  of  the  department  having 
jurisdiction.  (8-c.) 

401.  How  much  air  space  is  required  between  rheostat 
casing  and  supporting  surface? 

One -fourth  inch.     (78-b.) 

402.  How  must  rheostat  resistance  boxes  be  constructed? 
So  that  casing  will  only  make  actual  contact  at  points 

of  support  with  the  surface  upon  which  it  is  mounted.     (?8-b.) 

403.  How  must  lugs  for  currents  above  50  amperes  be 
fastened  to  terminals,  and  how  must  connecting  wires  be 
attached? 

Screwed  or  bolted;  connecting  wires  soldered;  ex- 
cept when  leads  designed  for  soldered  joints  connection  are 
provided.  (78-c.) 

404.  What  particular  markings  are  required  for  rheostats 
and  resistance  boxes? 

Must  be  plainly  marked  where  it  can  be  seen  after  in- 
stallation with  the  following:  Rating  and  name  of  maker; 
terminals  of  motor -starting  rheostats  must  be  correctly 
marked  with  circuit  name,  such  as  "line,"  "armature"  and 
"field."  (78-d.) 

405.  Is  it  obligatory  that  final  contact  upon  which  the 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      91 

rheostat  arm  rests  in  the  starting  position  be  out  of  elec- 
trical connection? 

Yes.     (78-e.) 

406.  Is  an  "eating"  arc  at  contact  when  circuit  is  broken 
sufficient  for  rejection,  if  it  happens  when  circuit  is  broken 
in  operation? 

Yes.     (78-e.) 

407.  Is  it  obligatory  for  all  motor-starting  rheostats  to  be 
BO  designed  that  a  contact  arm  cannot  be  left  on  an  inter- 
mediate segment;  and  for  direct-current  circuits,  what  are 
required? 

Yes.  For  direct  current,  automatic  device,  interrupt- 
ing supply  current  before  speed  falls  to  less  than  one-third 
of  normal,  is  necessary.  (78  -f.) 

Overload  Release. 

408.  What  overload  release  devices  are  approved? 

Only  those  operative  during  the  process  of  starting  a 
motor.  Exception  whenever  circuit-breakers  or  fuses  are 
properly  installed  in  connection  with  them.  (78-g.) 

409.  What  is  the  operative  test  for  rheostat  resistances 
(motor  starting)? 

After  100  operations  under  most  severe  normal  con- 
ditions, must  show  no  serious  burning  or  contact  or  other 
fire  hazard  fault,  and  release  mechanism  must  not  be  im- 
paired. (78-h.) 

Note  No.  32:  Above  is  a  manufacturer's  test  rather  than 
an  installation  requirement,  and  is  seldom  demanded  by 
insurance  inspectors.  It  applies,  nevertheless. 

410.  Must  field-regulation  or  main-line  rheostat  be  cap- 
able of  carrying  full  normal  load  at  any  step  for  an  indefinite 
period? 

Yes.     (78-h.) 

Auto  Starters. 

Questions  21  and  396,  397  and  401  to  410  where  applicable. 

411.  Under  ordinary  conditions,  i.e.,  when  not  exposed 
to  combustible  material  flyings,  or  in  dusty  or  linty  places, 
can  any  of  the  ordinary  approved  type  of  auto  starters  be 
used  instead  of  those  completely  metal  encased? 

Yes.     (79-a.) 

412.  How  must  apparatus  be  designed  for  starting  alter- 


92          QUESTIONS  AND  ANSWERS  ON  THE 

nating-current  motors  (not  auto  starters)  be  treated? 

See  questions  above  upon  rheostats,  and  Code  rule  78. 

413.  Must  auto  starters  comply  with  requirements  for 
wet,  dusty  or  linty  places  and  be  enclosed  in  dust-proof, 
fire-proof  cabinets? 

Yes,  unless  coming  equipped  with  tight  casings  en- 
closing current-carrying  parts.     (8-d.) 

414.  When  there  is  liability  of  creating  short  circuits 
across  exposed  live  parts  of  auto  starters,  what  precautic 
must  be  taken? 

Railing  must  be  erected  around  them.     (8-d.) 

415.  How  must  dust  cases  be  constructed? 
Accessible  to  inspection  and  renewal  of  oils.     Cash 

must  make  contact  only  at  points  of  support;  1/4  in.  air 
space  required  here.     (79-a.) 

416.  How  many  positions  must  an  auto  starting  switch 
show? 

One   "off"   or  running  position;  and  at    least  one 
starting  position.     (79 -a.) 

417.  May  switch  construction  be  such  that  the  starter 
may  be  left  in  the  starting  position;    or  that  a  properly 
running  overload  protective  device  does  not  really  protect 
the  circuit? 

No..     (79-a.) 

418.  Are  lugs  and  soldered  connecting  wires  required  fo 
terminal  connections  above  50  amperes? 

Yes.     (79-b.) 

Switches — All  Kinds,  Circuit  Breakers  and  cutouts. 

419.  Where  must  switches,  cut-outs  and  circuit-breaker 
be  located,  generally  speaking? 

In  readily    accessible  places;  in   plain  sight;  or   hi 
cabinets  away  from  combustible  materials. 

420.  May    switches,  -cut-outs    and    circuit-breakers    be 
openly  exposed  to  inflammable  gas,  dust  or  flying  combust- 
ible materials? 

No.     (i9-b.) 

421.  How  must  oil  switches  and  circuit-breakers  be  pro- 
tected under  conditions  described  in  last  question? 

In   dust-proof   cabinets   unless  dust-tight  casings. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE     93 

422.  May    circuit-breakers    take    the    place    of    service 
switches? 

Yes,  if  completely  disconnecting  all  supply  wires  and 
affording  protection  by  quick  action  against  overloads  and 
short  circuits.  Exceptions :  Grounded  circuits,  of  street  rail- 
way systems.  (iQ-a.) 

423.  How  far  from  floor  must  entrance  cut-out  or  service 
switch  be  located? 

Within  reach  wherever  practical.     (23 -a.) 

424.  Must  service  switches  cut  off  entire  current  from 
building? 

Yes.     (23 -a.) 

425.  How  must  service  outlet  be  located  with  relation  to 
the  service  switch  when  the  switch  is  inside  the  building? 

So  that  the  automatic  cut-out,  circuit-breaker  or 
fuses  used  will  protect  the  switch.  Must  be  located  before 
the  switch  and  between  service  wires  and  switch.  (23 -a.) 

426.  Must  yard  wires  on  private  plant  risks  run  from  build- 
ing to  building  be  protected  by  fuses? 

No,  if -next  fuse  back  is  small  enough  to  properly 
protect  wires  inside  building  supplied.  (23-3.) 

427.  When  must  cut-outs  invariably  be  used? 
Whenever  a  change  is  made  hi  the  size  of  the  wire, 

unless  the  cut-out  in  a  larger  wire  is  small  enough  to  protect 
the  smaller  wire.     (23  -b.) 

428.  Is  it  necessary  to  group  switches  as  far  as  possible? 
Yes.     (24-b.) 

429.  How  must  double-throw  switches  be  located? 
Double   throw  switches  may  be  mounted  so   that 

throw  will  be  either  vertical  or  horizontal,  as  preferred. 
(24-b.)     Horizontal  is  best  practice. 

430.  How  must  single-throw  knife  switches  be  installed? 
So  that  handle  will  be  down  when  open.     (24-b.) 

431.  How  must  three-way  switches  be  installed? 
As  if  single  pole.     (24-c.) 

432.  How  must  flush  switches  always  be  installed? 
In  approved  box  of  iron  or  steel.     (24 -d.) 

433.  Can  push  buttons  for  bells  and  other  similar  devices 
be  located  on  same  wall  plate  as  light  or  power  switch. 

No.     (24-d.) 

434.  How  must  surface  switches  be  mounted? 


94          QUESTIONS  AND  ANSWERS  ON  THE 

On  porcelain  or  approved  sub  bases,  except  that  in 
moulding  work  a  hard -wood  base  is  acceptable ;  or  approved 
base  may  be  mounted  directly  on  the  moulding.  (24 -f.) 

435.  Unless  outlet  boxes  are  supplied  at  concealed  work 
outlet  for  switches,    what  construction  must  be  used  to 
support  the  switch? 

Seven-eighth-inch  block  inside;  or  3/4-in.  wooden 
base  block  outside.  (24-6.)  See  also  similar  provision 
under  fixtures,  No.  676. 

436.  Where  must  cut-outs  be  located? 

In  readily  accessible  place,  in  plain  sight,  or  in 
accessible  cabinets.  (23-0.) 

437.  How  must  cover  of  switch  or  outlet  box  be  made 
when  box  is  installed  in  place  exposed  to  dampness? 

So  that  no  moisture  which  may  collect  on  top  or 
sides  of  box  can  enter  it.  (IQ-C.) 

Note  No.  33:     Slanting  top  construction  is  frequently  used. 

438.  How    must    flashers,    time    switches    and    similar 
appliances  be  installed? 

Enclosed  in  approved  metal  cabinets,     (ig-d.) 

439.  When  may  service  cut-out  be  omitted  from  neutra 
wire  of  a  three- wire  (not  three-phase)  system? 

When  neutral  is  grounded  in  approved  manner 
(23-b.) 

440.  How  must  ordinary  surface  switches,  cut-outs,  etc. 
when  exposed  to  moisture  and  not  enclosed  in  moisture- 
proof  boxes  be  treated? 

Mounted  on  porcelain  knobs.     (i9-c.) 

441.  When  may  single-pole    switches  be  placed    in 
neutral  wires  of  three- wire  systems? 

When  on  a  two -wire  branch  or  tap  supplying  not  nn 
than  660  watts.     (24-0.) 

442.  Is  it  necessary  for  service  cut-outs  and  switch  to  tw 
installed  and  arranged  to  protect  the  meter? 

Yes.     (24-a.) 

443.  Must  service  switches  indicate  on  inspection  whethe 
the  current  is  on  or  off? 

Yes.     (65 -a  and  b.) 

444.  Must  knife  switches  be  wired  so  that  they  are  a 
lutely  dead  at  one  end  when  open? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      95 
Yes.     (24-b.) 

Note  No.  34:  No  wires  except  those  governed  by  the 
switch  should  ever  be  inserted  under  binding  screws  or  otherwise 
attached. 

445.  Must  the  entire  supply  of  electricity  be  cut  off  from 
a  building  by  the  service  switch,  or  switches  where  different 
systems  or  services  enter? 

Yes.     (24-a.) 

446.  How  many  supporting  screws  must  knife  switches 
with  an  area  of  over  25  sq.  in.  base,  use? 

Four.     (65-0.) 

447.  Is  it  necessary  to  have  screws  or  washers  located 
1/2  in.  at  least  from  nearest  metal  live  part? 

Yes.     (6s-c.) 

448.  Whenever  supporting  screws  or  their  washers  are 
located  between  parts  of  opposite  polarity,  what  must  be 
done? 

Must  be  countersunk.     (65-0.) 

449.  May  a  250  volt  D.  C.  knife  switch  take  a  higher 
rating  for  A.  C.? 

Yes,  500  volts,  April,  1912,  List  of  Fittings. 

450.  What  is  operative  test  on  knife  switches? 

Fifty  per  cent,  of  rating  over  load  amperage ;  25  per 
cent,  excess  voltage.  Most  severe  practice  conditions.  (65 -i.) 

451.  May  300-ampere  switches  be    equipped    with   cut- 
out terminals. 

No.  See  Section  9,  Table  27,  [Code  table  IV.]  April, 
1912,  List  of  Fittings. 

452.  Where  cut-out  terminals  are  used  on  switches  over 
250  volts,  and  less  than  300  amperes,  what  marking  and 
fuse  spacing  must  be  used? 

Five  hundred  volts  alternating  current,  or  abbrevia- 
tion 500  V-A-C.  fuse  spacings  600  volts,  see  table  28  Sec.  9. 
(65-k.) 

453.  Should  auxiliary  breaks  or  their  equivalent  be  used 
on  direct-current-system  switches,  breaking  currents  greater 
than  100  amperes  (voltage  over  250)? 

Yes,  mandatory  for  all  direct -current  switches  over 
250  volts.  (65 -k.)  April,  1912,  List  of  Fittings. 

454.  What  separation  and  break  distances  for  plain  three- 


96          QUESTIONS  AND  ANSWERS  ON  THE 

pole  knife  switches,  single  throw,  must  be  observed  on  both 
three- wire  direct  current  and  three- wire  single-phase  systems? 

Must  not  be  less  than  as  indicated  for  neutral  and 
outside  wires  (65 -k  and  table  27,  Part  V,  Sec.  9). 

455-  When  must  switches  be  equipped  with  lugs,  screwed 
or  bolted  in  the  switch  for  the  proper  attachment  of  proper 
conductors? 

At  over  30  amperes  current.     (6s-h.)    Also  if  No.  8 
B.  &  S.  or  over  is  to  be  used.     (i6-c.) 

456.  Is  a  thoroughly  good  contact  at  fuses  a  Code  require- 
ment? 

Yes.     (67 -m.) 

Snap  Switches.     Read  431,  434,  440,  441  and  note  No.  33.  \ 

457.  What  is  the  limit  of  space  allowed  between  support- 
ing screws  and  current-carrying  parts  of  snap  switches? 

Three -sixty -fourths  inch.     (65-!.) 

458.  Are  requirements  for  metal,  and  especially  mechan- 
ical construction,  the  same  for  snap  switches  as  for  knife 
switches? 

Yes,  in  general  the  same.     (65 -f  and  65 -n.) 

459.  Are  switches  with  set  screwy  rejected? 

Fine  print  note  of  Code  declares  they  will  not  b 
approved.     (65-?.) 


460.  Can  the  insulated  or  uninsulated  handle  or  butto 


be  in  electrical  connection  with  the  circuit? 

Neither  handle  nor  any  exposed  part.     (65 -r.) 

461.  How  thick  must  the  insulating  lining  required 
snap  switch  covers  be  made,  and  must  it  extend  below  th 
edge  of  the  cover? 

Yes,  1/32  in.     (65 -q.) 

462.  Is  it   obligatory   that  insulated   lining  for   switch 
covers  be  fastened  securely? 

Yes.     (6s-q.) 

463.  Is  it  necessary  for  snap  and  flush  switches  to  b< 
marked,  and  how? 

Yes,  snap  switches  on  front  of  cover;  flush  switches 
may  be  placed  on  sub-plate.  Maker's  trade-mark,  curren- 
and  voltage.  (65  -t.) 

Circuit-breakers,  550  Volts  Maximum. 

464.  How  must  circuit-breakers  be  set? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      97 

Not  more  than  30  per  cent,  above  carrying  capacity 
of  the  wire,  unless  fusible  cut-out  is  also  used.     (23-6.) 

465.  Is  an  easily  accessible  means  of  tripping  breakers  by 
hand  required  under  the  Code? 

Yes.     (66-b.) 

466.  How  must  circuit-breakers  be  marked? 
Name  of  maker,  current  and  voltage.     (66-h.) 

467.  What    is    the    breaking    capacity   test   of   circuit- 
breakers? 

See  Table  No.  30,  Section  9,  Code  Rule  66-c. 

468.  Are   completely   disconnecting    circuit  breakers  al- 
lowed instead  of  fuses  when  circuit  load  is  greater  than  Code 
approved  fuse  limits  (see  table  25)? 

Yes.     (23-f.) 

469.  What    are    the    general    requirements    for   circuit- 
breakers  In  reference  to  bases,  installation,  etc. 

Same  as  those  for  rheostats  and  resistance  boxes. 

FUSES— ALL  KINDS— AND  ROSETTES 

Fuses. 

470.  When  are  link  fuses  allowed? 

Only   on   switchboards,    or    hi  fire -proof  cabinets, 
when  mounted  on  slate  or  marble  base.     (23-0.) 

471.  May  link  fused  rosettes,  properly  installed,  be  used 
on  open  work  in  large  mills,  and  what  are  the  limitations? 

Yes,  not  over  125  volts  circuit,  fuses  not  over  3 
amperes,  and  amperage  limit,  25.     (23-d.) 

472.  Are  link  fuses  approved  upon  approved  enclosed 
rosettes  in  large  mills? 

Yes.     [23-d.] 

473.  How  must  copper-  or  brass- tipped  fuses  be  stamped? 
Eighty  per  cent,  maximum  current  carried  indefi- 
nitely.    (68-b.) 

474.  Is  it  obligatory  for  the  contact  tips  to  be  in  good 
electrical  connection  with  the  fuses? 

Yes.     (58-a.) 

475.  What   is   the  largest   amperage  on  branch   circuits 
in  large  mills  where  rosettes  are  used? 

Twenty-five  amperes.     (23-d.) 
7 


98       QUESTIONS  AND  ANSWERS  ON  THE 

476.  May  enclosed  fuses  be  used  in  large  mills  up  to  250 

volts,  when  applied  in  rosettes,  and  what  is  the  limitation? 

Yes,  3  amperes,  in  approved  "enclosed  fused"  rosettes; 

branch  circuit  protection  to  be  not  more  than  25  amperes, 

250  volts  maximum.     (23-d.) 

477-  What  spacings  are  required  for 

First,  open  link  fuses  not  over  125  volts? 
Second,  open  link  fuses  not  over  250  volts? 
Third,  open  link  fuses  not  over  250  volts  under 
alternating-current  systems? 

See  Table  No.  23,  Section  Nine  (9). 

478.  Is  an  automatic  cut-out,  such  as  a  main  fuse,  required 
by  the  Code  upon  all  installations  to  cut  off  the  entire  current 
from  the  building? 

Yes.     (23-a.) 

Enclosed  Fuses — Plug  and  Cartridge  Type. 

See  also  Tables  24,  25  and  26,  Section  9. 

Following  questions  do  not  apply  on  fuses  for  rosettes, 
attachment  plugs,  car  lighting  cut-outs,  and  signalling  sys- 
tem protective  devices. 

479.  Is  it  necessary  for  fuse  casings  to  be  dust-proof  type? 
Sufficiently  to  prevent  lint  and  dust  collection  around 

the  fuse.     (68-d.) 

480.  Does  the  National  Code  approve  of  the  practice  of 
refilling  plug  fuses,  limited  30  amperes,  except  by  manufac- 
turers or  skilled  persons? 

No.     (68-d.) 

481.  Must  fuses  be  marked  "National  Code  Standard"? 
Yes.     (68-i.)     Abbreviation  "N.  E.  Code  St'd."  ac- 
ceptable. 

482.  What  are  the  prescribed  label  colors  for  250  volt 
fuses? 

Green.     (68-i.) 

483.  For  600  volt  fuses? 
Red.     (68-i.) 

484.  What  is  the  heating  limit  for  enclosed  fuses? 
Outside  may  not  rise  more  than  125°  F.  [70  degrees 

Centigrade]    above    surrounding  air  at  its    rated  current. 
(68-j.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE      99 

Rosettes — All  Kinds. 

485.  How  must  supporting  screws  be  located  or  counter- 
:  sunk? 

So  that  flexible  cord  cannot  come  in  contact  with 
them.     (7 1 -a.) 

486.  What  space  is  required  between  supporting  screws 
and  current-carrying  parts? 

One -fourth  inch.     (71 -a.) 

487.  How  far  from  surface  wired  over  must  rosette  keep 
wire? 

One -half  inch.     (71 -a.) 

488.  How  many  screws  are  required  for  knob  and  cleat 
type  rosette  base  support? 

Two.  (7 1 -a.) 

489.  How  high  must  moulding  and  conduit  box  types 
rosette    keep    wires    and    terminals    from    surface    wired 
over? 

Three -eighth  inch.     (71 -a.) 

490.  Is  a  porcelain  lug  on  knob  and  cle.at  type  rosettes 
obligatory? 

Yes,  sufficient  to  prevent  rosette  from  being  so  placed 
as  to  reduce  wire  separation  to  less  than  1/2  hi.     (71 -a.) 

491.  Is  space  for  knotting  of  flexible  cord  necessary,  and 
how  much? 

Yes  (7i-e);   space  recommended  for  standard  port- 
able cord  [and  others]  13/32  in.     (71  -d.) 

492.  Is  it  obligatory  that  the  surfaces  upon  which  a  flex- 
|  ible  cord  knot  rests  in  the  rosette  be  smooth  and   well 
!  rounded? 

Yes.     (71-6.) 

493.  How  must  cover  on  a  two-piece  rosette  fasten? 
So  that  it  cannot  work  loose  from  base.     (7i-f.) 

Fused  Rosettes.      . 

494.  In  fused  rosettes  especially,  must  cover  fit  closely 
over  base? 

Yes.     (7i-f.) 

495.  Is  it  obligatory  that  fused  rosettes  have  a  fuse  in 
each  pole? 

Yes.     (7i-h.) 


100       QUESTIONS  AND  ANSWERS  ON  THE 
CABINETS  AND  PANEL  BOARDS— ALL  KINDS 

Read  Questions  419  and  655.     Code  Rules  19-b  and  c. 
34- d,  and  70-f  and  g.  also  applicable. 

Cabinets.     (Questions  505-509  apply  all  kinds  of  cabinet 

496.  Must  cabinets  be  marked  and  how? 

"With  manufacturer's  name  where  it  can  be  plainly 
seen,  when  cabinet  is  installed."     (7o-h.) 

497.  What  kind  of  cabinets  are  approved? 

Cast  or  sheet  metal;  wood  or  approved  composition, 
properly  applied.     (7o-b.) 

498.  May  wooden  or  composition  cabinets  be  used  on 
metallic  protective  systems? 

No.     (7o-b.) 

499.  Is  it  necessary  to  thoroughly  paint  metal  used 
cabinet  construction? 

Yes.     (7o-b.) 

Note  No.  35 :     Cabinets  are  the  enclosures  for  slate  or  ot 
non-combustible  insulating  material  of  the  electrical  devices 
and  include  all  parts  of  the  box  or  enclosure.     When  back  ij  j 
of  insulating  material  and  is  properly  fastened  so  as  to  fora 
an  integral  part,  this  is  also  considered  a  part  of  the  cabinet 

Woodea  Cabinets. 

500.  Is  it  necessary  to  fill  and  paint  a  wooden  cabinet? 
Yes.     (7o-c.) 

Note  No.  36:  The  application  of  any  liquid  or  semi-liquic 
vegetable  oil,  paint,  dressing,  or  composition  will  close  up  th( 
pores  of  the  wood  as  is  frequently  done  in  hard  wood  floors 

501.  Must  wooden  cabinets  be  lined  with  asbestos  board 
or  other  non-combustible  material? 

Yes,  1/8  in.  thick.     (7o-c  and  d.) 

502.  What  is  the  kind  and  smallest  thickness  of  wood 
permitted? 

Seasoned  3/4  in.   '  (70-0.) 

503.  Are  screws  or  tacks  acceptable  for  fastening  in  place 
1/8"  rigid  asbestos  board  as  a  cabinet  lining? 

Yes.     (7o-d.) 

504.  What   is   the   regulation   distance   for   spacing   in 
cabinets  in  general  between  walls,  back  or  door,  and  any 
exposed  live  metal  part? 

One-half  inch.     (7o-a.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    101 

505.  When  is  it  necessary  to  make  cabinet  deep  enough 
to  allow  doors  to  be  closed  on  switches  in  any  position? 

When  switch  is  30  amperes  or  less.     (7<>-a.) 

506.  When  switches  larger  than  30  amperes  are  installed 
in  cabinets,  what  construction  is  necessary? 

Cabinet  must  be  deep  enough  to  permit  switch  to  be 
thrown  as  wide  open  as  its  construction,  or  the  limits  of  the 
installation  conditions  will  permit.  (70 -a.) 

507.  Is  it  obligatory  that  cabinets  be  substantial  and  dust- 
proof? 

Yes.     (7o-a.) 

508.  On  unlined  doors  of  metal  which  are  less  than  0.109 
in.  (Xo.  12  Sheet  Metal  Gauge)  how  much  space  must  be 
kept  between  door  and  enclosed  fuses  and  any  live  metal 
part  at  all  times? 

One  inch.     (7o-a.) 

509.  Where  link  fuses  are  used  in  cabinets,  what  space 
must  be  provided  between  them  and  metal,  metal-lined,  or 
glass-panelled  cabinet  doors? 

At  least  2  in.     (7o-a.) 

Panel  Boards. 

Following  questions  do  not  apply  to  central  station  switch- 
boards, or  switchboards  with  primary  control  of  generators 
or  transformed  energy,  including  isolated  plants.  (69,  fine 
print  note.) 

510.  Must  tablets  and  panel  boards  bear  manufacturer's 
name,  voltage  design  and  maximum  capacity  of  amperage? 

Yes.     (69-c.) 

511.  How  must  tablet  or  panel  boards  be  designed  with 
reference  to  the  relative  arrangement  of  fuses  and  switches, 
epacings  of  same,  etc.? 

Comply  hi  general  with  space  requirements  for 
switches,  cut-outs,  etc.  See  Tables  No.  27-29.  (69-a-b  and 
7o-a.) 

512.  Must  fuses  be  placed  between  busbars  and  switches 
or  oppositely  in  front  of  the  switch,  i.e.,  between  switches 
and  circuits? 

Either  is  acceptable,  except  in  case  of  service  switches. 
(69-a.)  See  No.  424-425. 


102  OFFICIAL  NATIONAL  ELECTRICAL  CODE 

513.  How  close  may  exposed  live  metal  parts  on  back  ol 
board  come  to  cabinet  on  which  board  is  mounted? 

Must  be  kept  away  not  less  than  1/2  in.     (69 -a.) 

514.  Is  it  necessary  when  branch  switches  are  betweer 
fuses  and  busbars  for  connections  to  be  so  arranged  thaSl 
blades  will  be  dead  when  switches  are  open? 

Yes.     (69-a.) 

515.  Give  minimum  spacings  between  bare  live 
parts,  busbars,  etc. 

See  Table  No.  29,  Section  9. 


SECTION  SIX 
DIVISION  FOUR 

THEATERS  AND   MOVING   PICTURE   SHOWS  IN 
GENERAL 

Emergency  Lights,  Stage  Work-construction,  Stage  Work, 
wattage  Limits,  Foot  Lights,  Border  and  Proscenium  Side 
Lights,  Border  Wiring,  Stage  and  Gallery  Receptacles, 
Scene  Docks,  Curtain  Motors,  Minimum  Thickness  Metal, 
Bunch  Lights,  Strips,  Portable  Plugging  Boxes,  Pin  Plug 
Connectors,  Portable  Conductors,  Lights  on  Scenery, 
String  or  Festoon  Lights,  Special  Electrical  Effects,  Dressing 
Rooms,  Arc  Lamps  for  Stage  Effects — Portable,  Competent 
Operators,  Stage  Flue  Control. 

MOVING  PICTURE  EQUIPMENTS 

Reels  with  Films  under  Examination  or  Rewinding,  Auto- 
matic Shutter,  Extra  Films,  Machine  Operation,  Machine 
Installation. 

OUTLINE  LIGHTING      . 
Wattage  and  Receptacle  Limits,  Sockets  and  Receptacles 

ELECTRIC   SIGNS 
Installation  and  Wattage  Limits. 
In  General. 

DECORATIVE  LIGHTING  SYSTEM 

ELECTRIC   HEATERS   FOR   GENERAL  USE 

MERCURY  VAPOR  LAMPS,  HIGH  POTENTIAL  VACUUM 

TUBE   SYSTEMS 
Grounding. 
Mercury  Vapor  Lamps — Enclosed. 


103 


SECTION  SIX 

DIVISION  FOUR 

THEATERS  AND  MOVING  PICTURE  SHOWS  IN  GENERAL 

Following  questions  apply  more  particularly  to  theaters 
I  and  moving  picture  shows  and  their  details.  Unless  other- 
wise indicated  all  rules  and  requirements  of  the  National 
jiCode  Class  "C"  (Inside  Wiring)  apply. 

The  code  defines  buildings  under  this  heading  as  follows: 

"A  building  of  that  part  of  a  building  regularly  or  frequently 
used  for  dramatic,  operatic,  moving  picture  or  other  per- 
formances or  shows,  or  which  has  a  stage  for  such  performances 
used  with  scenery  or  other  stage  appliance."  (38.) 

516.  When  are  two  separate  and  distinct  services  re- 
quired? 

Whenever  supply  may  be  obtained  from  two  separate 
street  mains.  (s8-a.) 

517.  What   capacity   and   application   must   these   two 
services  have? 

The  first  sufficient  to  supply  current  for  entire 
equipment  of  theater,  and  the  second,  at  least  a  sufficient 
capacity  to  supply  current  for  all  emergency  lights.  (38-3.) 

518.  Where  supply  cannot  be  obtained  from  two  separate 
sources,  where  must  feed  for  emergency  lights  be  taken? 

From  point  on  street  side  of  main  service  fuses. 
(38-a.) 

Note  No.  37:  Intention  is  to  ensure  fire  hazard  protection 
(as  well  as  life)  by  minimizing  any  possible  interruption  to 
emergency  lights. 

Emergency  Lights. 

519.  Define  emergency  lights. 

Exit  lights,  all  lights  in  lobbies,  stairways,  corridors, 
and  other  parts  of  theater  to  which  public  have  access,  which 
are  normally  kept  lighted  during  the  performance.  (38-3.) 

Note  No.  38:  Theater  arrangements  should  always  in- 
clude lights  marking  exits,  fire  escapes  and  similar  places  for 
guidance  of  audience  in  case  of  fire  or  panic. 

520.  When  must  there  be  an  auxiliary  service  to  supply  a 
theater? 

105 


106        QUESTIONS  AND  ANSWERS  ON  THE 


J 


When  main  source  of  supply  is  inside  the  buildi 
an  auxiliary  service  for  emergency  lights  particularly  mus 
be  taken  from  before  fuses  of  a  street  main ;  a  storage  batter] 
within  the  premises  is  regarded  as  an  equivalent.  (3 8 -a. 

521.  How  many  fuses  may  exit  lights  have  between  then 
and  the  service  fuses? 

Not  more  than  one  set  and  in  cabinets.     (38-t.) 

522.  May  exit  and  audience  lights  be  controlled  excep 
from  lobby  or  other  quickly  accessible  place  in  front  of 
house? 

No.  (38-t.) 

523.  May  exit  and  audience   lights  be  placed  on 
lighting  circuit? 

No;  must  be  fed  independently  of  stage  light 
(38-t.) 

524.  Are  general  auditorium  lights  included  in  audienc 
lights? 

No.     (38-a.) 

Stage  Work — Construction. 

525.  What  kind  of  permanent  construction  must  be  use* 
on  stage  side  of  proscenium  wall  of  theater? 

Conduit  or  approved  armored  cable.  (s8-b. 
Exceptions :  Borders  and  other  necessarily  flexible  installa 
tions,  as  indicated  by  the  questions  upon  the  particular  piec 
of  apparatus  or  appliance.  (38-b.) 

526.  Are  wooden  switchboards  permitted  for  theaters? 
No.     (38-c.) 

527.  When  must  stage  switchboards  be  protected  by 
guard  rail? 

Whenever  accessible  from  the  stage  level.     (38-0.) 

Wattage  Limits— Stage  Work. 

528.  Is  it  necessary  to  solder  wires  to  lugs  of  all  recej 
tacles  in  foots,  border  and  proscenium  side  lights? 

Yes.     (38-d,  38-6-3.) 

529.  Give  wattage  limit  and  greatest  number  of    recej 
tacles    dependent    upon    one    cut-out  permitted  on  foot: 
borders,  and  proscenium  stage  lights. 

1320  watts;  24  receptacles.     (38-d  and  38-6-2.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   107 

Footlights. 

530.  Must  receptacles  in  footlights  be  enclosed  in  approved 
outlet  boxes,  or  will  lamp  receptacles  mounted  in  iron  or 
steel  box  be  approved? 

Either  method  is  approved,  with  an  approved  con- 
duit or  armored  cable  enclosing  the  conductors  supplying 
same.  (38-d.) 

531.  Is  a  steel  trough  built  to  enclose  live  parts  of  recep- 
tacles and  to  contain  all  wires,  acceptable? 

Yes,  if  not  less  than  20  U.  S.  sheet  metal  gauge,  en- 
closing all  wires.  (38-d.) 

532.  Must  wires  be  soldered  to  receptacle  lugs  for  foot- 
lights? 

Yes.     (38-d.) 

Borders  and  Proscenium  Side  Lights. 

533.  How  must  troughs   be    treated  for  borders,    pro- 
scenium side  lights  and  as  otherwise  used? 

Be  painted  to  prevent  oxidation,  or  otherwise  treated ; 
be  suitably  supported  and  stayed.  (38-6-1.) 

534.  Where  flanges  of  a  border  light  trough  are  arranged 
to  protect  lamps  from  mechanical  injury,  is  this  acceptable 
instead  of  wire  guards  or  meshing? 

Yes.     (38-6-1.) 

535.  What  kind  of  guards  are  necessary  to  prevent  con- 
tact of  scenery  or  other  combustible  material  with  the  lamps 
in  borders  and  proscenium  sidelights? 

"Suitable  guards."     (38-6-4.) 

Note  No.  39:     Wire  netting  serves. 
Border  Wiring. 

536.  What  kind  of  wire  must  be  used  for  wiring  borders? 
Approved  slow-burning  insulation.     (38-6-6.)     Type 

letter  S.  B. 

537.  What  kind  of  cables  must  be  used  for  borders? 
Type  letter  B.     See  Table  No.  16,  Section  9. 

538.  How  must  border  trough  be  suspended? 

By  at  least  one  strain  insulator  inserted  at  border  if 
a  wire  rope  is  used.  (38-6-7.) 

539.  What  construction  is  specific  from  switchboard  to 
where  border  cable  begins? 


108        QUESTIONS  AND  ANSWERS  ON  THE 

Conduit  construction.     (38-6-5.) 
Stago  and  Gallery  Receptacles. 

540.  Must  stage  and  gallery  pockets  be  controlled  from 
switchboard? 

Yes.     (38-f.) 

541.  Must  they  be  of  approved  type? 
Yes.     (38-1.) 

542.  Can  plugs  for  arcs  and  incandescent  pockets  be 
interchangeable  ? 

No.     (38-f.) 

543.  Give  rating  for  each  receptacle  for  an  arc  lamp. 
Thirty-five  amperes.     (38-f.) 

544.  Give  rating  for  a  stage  receptacle  for  incandescent 
lamps. 

Not  less  than  15  amperes.     (38-f.) 

545.  Must  both  arc  lamp  and  incandescent  lamp  recep- 
tacles be  wired  to  full  capacity? 

Yes.     (38-f.) 

546.  What  size  wire  must  be  used  for  arc  lamp  pockets? 
No  smaller  than  No.  6  B.  &  S.     (38-f.) 

547.  What  is  the  smallest  size  wire  permitted  for  an 
incandescent  pocket? 

No.  12  B.  &  S.     (38-f.) 

Scene  Docks. 

548.  What  special  precaution  must  be  taken  for  location 
of  lamps  in  scene  docks? 

Must  not  be  liable  to  mechanical  injury.     (38-g.) 
Curtain  Motors. 

549.  What  type  of  motors  must  be  used  for  curtain 
motors? 

Iron  clad  type.     (38-h.) 

Minimum  Thickness  Metal. 

550.  Give  minimum  thickness  border,  strip,  and  footlight 
metal? 

No.  20  TJ.  S.  sheet  metal  gauge.     38-6-1,  38-m  and 
38-d. 

Bunch  Lights. 

551.  May  bunch  lights  contain  any  exposed  wiring? 
No.     (38-1.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   109 

552.  Is  it  required  that  cables  feeding  bunch  lights  be 
fastened  to  prevent  mechanical  strain? 

Yes.     (38-1.) 

553-  Is  a  bushing  necessary  where  cable  passes  through 
metal,  in  order  to  prevent  abrasion? 
Yes.     (38-l.) 

Note  No.  40:  Above  applies  to  borders,  foots,  and  all  kinds 
of  appliances  on  stage  as  well  as  off.  Provision  that  mechanical 
strain  be  avoided  is  also  general. 

Strips. 

554.  How  must  wiring  be  done  for  strips? 

Approved  conduit  or  armored  cable,  with  lamp 
receptacle  in  boxes;  or  all  wires  enclosed  in  iron  or  steel 
box.  (38-01.) 

555.  How  must  strips  be  built  and  hung? 

Flanged  to  protect  lamps;  properly  stayed  and  sup- 
ported and  made  of  steel  thickness  No.  20  U.  S.  M.  gauge. 
(38-m.) 


Portable  Plugging  Boxes. 

556.  Are  boxes  with  exposed  carrying  parts  approved? 
No.     (38-n.) 

557.  Are  approved  fuses  with  slate  or  marble  bases  ob- 
ligatory for  each  receptacle? 

Yes.     (38-n.) 

558.  How  must  fuses  for  portable  plugging  boxes  be  en- 
closed? 

In    fire-proof    cabinet    with    self-closing    doors. 
(38-n.) 

559.  What  must  be  the  capacity  of  each  receptacle  in  a 
portable  plugging  box? 

Thirty  amperes;  without  undue  heating.     (38-n.) 

560.  How  much  current  must  the  busbars  of  each  port- 
able plugging  box  carry  without  undue  heating? 

Equal  to  the  amount  required  by  all  the  receptacles 
fed  by  the  box.     (38-n.) 

Pin  Plug  Connectors. 

561.  Must  pin  plug  connectors  be  of  approved  type? 
Yes.     "So  that  female  part  of  plug  will  be  on  live 

end  of  cable;  and  must  be  constructed  so  that  tension  on 


110       QUESTIONS  AND  ANSWERS  ON  THE 

the  cable  will  not  cause  serious  strain  on  the  connections." 

(38-0.) 

Portable  Conductors. 

562.  What  is  the  limit  for  stand  lamps  where  conditions 
are  such  as  to  justify  the  use  of  ordinary  approved  ("P" 
type  letter)  reenforced  cord,  for  protection  from  mechan- 
ical injury? 

Six  amperes.     (3 8 -p.) 

563.  Does  the  above  apply  to  all  arcs,  bunches  and  other 
portable  equipments  used  in  stage  business,  and  what  kind 
of  cable  is  required  in  order  that  a  higher  amperage  may 
be  used? 

No,    approved   stage  cable.  (38-?.)  (Type  letter  T.) 
See  also  table  16. 

Lights  on  Scenery. 

564.  Must  brackets  for  use  on  stage  scenery  be  wired 
inside? 

Yes.     (38-q.) 

565.  How  far  must  such  brackets  project  in  the  rear? 
"Fixture  stem  must  come  through  to  the  back  of 

scenery  and  be  properly  bushed."     (38-q.) 

String  or  Festoon  Lights. 

566.  What  kind  of  wire  may  be  used  for  string  or  festoon 
lights  under  ordinary  conditions? 

Rubber-covered.     (38-1.) 

567.  Must  guards  be  used  for  lanterns  or  similar  devices? 
Yes.     (38-r.) 

568.  Is  it  necessary  to  tape  and  solder  joints  for  string  and 
festoon  lights? 

Yes.     (38-r.) 

569.  How  must  such  joints  be  located  in  wires? 
Staggered.     (38-r.) 

Note  No.   41:     "Staggered"   means   alternating  joints,   so 
that  no  two  will  come  close  together. 

Special  Electrical  Effects. 

570.  For  devices  for  producing  lightning,  water-falls,  etc., 
what  special  protection  must  be  given? 

' 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   111 

Location  must  be  such  that  sparks  cannot  come  in 
itact  with  combustible  materials.     (38-3.) 

ing  Rooms. 

71.  How  must  dressing  room  pendant  lights  be  installed? 
Approved  reinforced  cord  (type  letter  "P"  or  P.  Wp.) 
armored  cable  type  A.  C.  or  steel  armojed  flexible  cord 
(type  letter  P.  A.)  (38-j.) 

572.  Are  approved  lamp  guards  required  for  all  lamps  in 
iressing  rooms? 

Yes.     (38-j.) 

\ic  Lamps  for  Stage  Effects — Portable. 

573.  Is  any  substitute  for  metal  allowed  in  the  construc- 
iion  of  a  stage  effect  arc  lamp? 

No,  except  where  use  of  approved  insulating  material 
s  necessary.     (38-k-i.) 

574.  Is  construction  of  stage  arc  lamps  so  that  proper 
ventilation,    confinement  of  sparks  within,   and  'mica  for 
:he  frame  insulation  necessary? 

Yes.     (38-k-2.) 

575.  Is    self-closing    hinged    wire    gauze   or   glass   door 
equired  for  front  openings  of  doors  of  stage  lamps? 

Yes,   except   hi   lens   lamps,   where   front  may   be 
tationary  and  solid  door  used  on  back  or  side.     (38-k-3.) 

576.  Is  a  construction  that  will  keep  arc  lamp  carbons  and 
ive  parts  away  from  liability  of  contact  with  metal  hood 
luring  operation  necessary? 

Yes,  arc  lamp  frames  and  standards  must  be  so  con- 
tructed  as  to  prevent  grounding  liability.     (38-k-4.) 
jl  577.  Are  knife  switches  allowed  on  lamp  stands? 

No,  unless  so  enclosed  and  protected  that  accidental 
[ive  contact  is  impossible.     (38-k-5.) 

|   578.  Are  approved  lugs  necessary  for  stranded  connec- 
ions  in  lamp  and  at  switch  and  rheostat? 

Yes.     (38-k-6.) 

!  579-  How  high  from  floor  must  rheostat  on  portable  thea- 
sr  arc  lamp  stand  be  located? 
At  least  3  in.     (38-k-7.) 

580.  Is  it   obligatory  that  rheostats  for  arc  lamps  be 
lainly  marked  with  the  rated  capacity  in  volts  and  amperes? 


112       QUESTIONS  AND  ANSWERS  ON  THE 

Yes.     (38-k-7.) 

581.  Is  it  obligatory  that  resistance  be  enclosed  in  a  sul 
stantial  and  properly  ventilated  metal  case? 

Yes.     (38-k-7.) 

582.  How  much  clearance  must  be  afforded  between  fac 
and  resistance  clement? 

One  inch. 


Competent  Operator. 

583.  What  is  the   greatest   number   of   arc   lamps   on 
operator  may  watch,  and  under  what  conditions? 

Two;  not  more  than  10  ft.  apart  and  located  so  ths 
he  can  properly  watch  and  care  for  both  lamps.     (38-k-8, 

584.  Is  the  employment  of  a  competent  operator  to  cai 
for  not  more  than  two  lamps  located  as  in  last  questioi 
obligatory? 

Yes.     (38-k-8.) 


Stage  Flue  Control. 


585.  Can  the  so-called  open  circuit  system  (normally)  I 
used  for  electric  release  of  dampers? 

No.  (38-i.) 

586.  Must  operating  magnet  take  full  voltage  of  supp 
circuit  without  resistance  devices? 

Yes.     (38-1.) 

587.  Must  operating  magnet  on  damper  in  full  operatic 
have  normal  heating  limit? 

Yes.     (38-1.) 

588.  How  must  magnet  be  located  and  installed? 

In  loft  above  scenery  and  installed  in  suitable  iron  b« 
with  self  -closing  door.  (38-!.) 

589.  How  many  switches  are  required,   and  how  mu 
dampers  be  controlled? 

Two  single -pole  switches  in  iron  boxes  approv 
and  with  self  -closing  doors  without  lock  or  latch;  o 
switch  located  at  electrician's  station  and  others  as  d« 
ignated  by  the  insurance  department  having  jurisdictic 
(38-u-f.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   113 
MOVING  PICTURE  EQUIPMENT 

590.  How  must  arc  lamps  used  as  part  of  moving  picture 
machine  outfits  be  constructed? 

Same  requirements  as  arc  lamps  of  theater.  See 
questions  Nos.  573  to  582  inclusive.  Division  4.  (38-11-1.) 

591.  What  is  the  smallest  size  conductor  permitted  for 
arc  lamps? 

No  less  than  No.  6,  B.  &  S.     (38-u-i.) 

592.  How  must  moving  picture  rheostats  be  installed? 
Must  conform  to  theater  arcs.  See  Questions  579  to 

582  inclusive.     (38-U-2.) 

593.  Is  it  necessary  to  enclose  top  and  bottom  reels  in 
flame-proof  steel  magazines  or  boxes? 

Yes.     (38-11-3.) 

594.  Can  solder  be  used  on  these  boxes  or  magazines? 
No.     (38-U-3.) 

Reel  with  Films  under  Examination  or  Rewinding. 

595.  How  must  reels  containing  films  as  above  be  kept? 
In  magazines  or  approved  metal  boxes;  not  more 

than  2  ft.  of  film  exposed  in  booth.     (38-u-S.) 

596.  How  must  the  openings  be  made  in  the  boxes  or 
magazine? 

Front  side  consists  of  door,  spring  hinged,  and  swing- 
ing horizontally  and  provided  with  substantial  latch.  (38- 
u-30 

Automatic  Shutter. 

597.  How  must  shutter  operate  to  prevent  action  of  the 
beam  of  light  upon  the  inflammable  film  when  film  is  not 
running  at  operating  speed? 

Shutter  must  shield  automatically.     (38-U-4.) 

598.  Is  it  obligatory  that  shutter  be  permanently  attached 
to  gate  frame? 

Yes.     (38-U-4-) 
Extra  Films. 

599.  How  must  extra  films  be  kept? 

In  individual  metal  boxes  with  tight-fitting  covers. 
(38-u-s.) 
8 


114       QUESTIONS  AND  ANSWERS  ON  THE 

Machine  Operation. 

600.  Are  motor-driven  machines  permitted? 
Yes,  under  following : 

"6.  Machine. — Must  be  of  an  approved  type.  If  driven  by 
a  motor  must  be  of  a  type  expressly  designed  and  approved  for 
such  operation,  and  when  so  approved,  motor  driven  machines, 
when  in  charge  of  a  skilled  operator,  may  be  permitted  by  the 
Inspection  Department  having  jurisdiction."  Promulgated 
April,  1912,  List  of  Fittings." 


Machine  Installation. 

60 1.  How  must  machines  as  a  whole  be  installed? 

Machine  Enclosure. — Machine  must  be  placed  in 
an  enclosure  or  house  made  of  suitable  fire -proof  material; 
must  be  properly  ventilated,  properly  lighted  and  large  enough 
for  operator  to  walk  freely  on  either  side  of  or  back  of  ma- 
chine. All  openings  into  this  booth  must  be  arranged  so  as 
to  be  entirely  closed  by  doors  or  shutters  constructed  of  the 
same  or  equally  good  fire -resisting  material  as  the  booth 
itself.  Doors  or  covers  must  be  arranged  so  as  to  be  held 
normally  closed  by  spring  hinges  or  equivalent  devices. 
(38-u-7.) 


OUTLINE   LIGHTING 

Low  Potential — 550  to  10  Volts. 

Wiring — other  than  signs  on  exterior  of  buildings.     See 
619. 

Note  No.  42:     This  class  of  wiring  applies  in  distinction  to 
so-called  temporary  lighting. 

602.  Is  any  kind  of  moulding  permitted  for  outline  wiring? 
No.     (39-b.) 

603.  What  three  kinds  of  work  are  permitted  for  outline 
wiring? 

Open    work    with     rubber -covered    wire.     Conduit 
work.    (39-b.)    Lead  sheathed  armored  cable  also.    (39-6.) 

604.  How  must  wires  for  open  work  be  installed? 

i   in.  from  surface  wired  over;  2  1/2  in.  apart  up 
to  300  volts.    4  in.  apart  if  over  300  volts ;  (39-c.) 

605.  Is  it  necessary  to  seal  the  ends  of  flexible  tubing 
when  used  in  this  work? 

Yes.     (39-d.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   115 

606.  If  flexible  tubing  is  applied,  must  it  be  kept  away 
from  the  surface  wired  over? 

Yes,  must  be  knob -mounted  or  otherwise  supported 
a  half  inch  at  least  from  surface  wired  over.  (39-d.) 

607.  Must  wires  for  use  in  rigid  or  flexible  steel  conduit 
on  outline  wiring  be  of  special  insulation? 

Yes,  type  letter  R-D  wire  (has  1/32  extra  fibrous 
covering)  for  wire  larger  than  No.  10;  at  least  1/64  extra 
for  wires  No.  10  or  less  is  required  for  unlined  conduit  work. 
(39 -e.)  See  table  8. 

608.  What  kind  of  protective  covering  must  be  used 
where  armored  cable  is  applied? 

Armored  cable  must  be  of  lead  sheathed  type,  with 
sheath  between  armor  and  insulation.  (39-6.) 

609.  Is  separate  controlling  switch  and  cut-out  required 
for  outline  lighting  systems? 

Yes.     (39-f.) 

610.  What  precaution  must  be  taken  with  switches,  cut- 
outs, flashers,  time  switches  and  similar  appliances  where 
located  outside  of  building. 

Enclosed  in  steel  or  cast-iron  box.     (39-f.) 

6 1 1.  How  must  above  appliances  be  installed  where  lo- 
cated inside  of  building? 

According  to  Code  requirements  for  such  devices, 
as  indicated  by  Question  No.  438,  Section  6,  Inside  Wiring. 

(39-fO 

612.  What  is  the  minimum  thickness  allowed  for  a  steel 
box  used  on  outline  lighting  enclosures  at  switches,  etc.? 

No.  ii  U.  S.  sheet  metal  gauge,  or  0.125  in.     (39-f.) 

613.  How  far  must  knife  switch  clear  a  door  in  an  outside 
steel  box? 

One  inch.     (39-gO 

614.  Is   it   necessary   for   boxes   to   be   moisture   proof 
whether  inside  or  outside? 

Yes.     (39-g.) 
Wattage  and  Receptacle  Limits. 

615.  What  is  the  wattage  limit  of  a  circuit  dependent  upon 
one  double  pole  cut-out? 

1320  watts.     (39-h.) 

6 1 6.  What  number  of  sockets   or  receptacles  may  be 
connected  to  a  single  circuit? 


116       QUESTIONS  AND  ANSWERS  ON  THE 

Sixty-six,     (39-h.) 
Sockets  and  Receptacles. 

617.  What  kind  of  sockets  and  receptacles  must  be  used? 
Keyless,  porcelain  type.     (39-!.) 

6 1 8.  Must   wires   be   soldered   to   lugs   on   sockets   and 
receptacles? 

Yes.     (39-i.) 


ELECTRIC  SIGNS 
(On  550  volts  or  less) 
Installation  and  Wattage  Limits. 

619.  What  is  the  allowance  of  sign  and  outline  wiring 
circuit  fuses  of  55  volts  or  less? 

Twenty -five  amperes.     (23-d.) 

620.  What  is  wattage  limit  on  final  cut-out  for  electric 
sign  circuits? 

1320  watts.     (83 -g.) 

In  General. 

621.  May  approved  receptacles  alone  support  the  wires? 
Yes,   if  supporting  every  foot;  holding  one  inch 

high;  2  1/2  inches  apart     (83-6.) 

622.  Is  open  work  wiring  permitted  for  signs,  and  where? 
Only  on  roofs  or  open  ground  where  not  subject  to 

mechanical  injury.     (83  -b.)     Read  643. 

623.  How  must  wiring  up  to  an  open  work  sign  be  done? 
Open  work,  Conduit,  or  armored  cable  (83-6).    See 

Question  631. 

624.  In  open  work  signs  (wires  not  enclosed  with  any 
metal    conduit),    what   is   the   space   limit   for   receptacle 
terminals  from  each  other  and  from  the  sign  metal? 

One  inch.     (83-d.) 

625.  In  passing  through  walls  or  partitions  of  a  wooden 
or  a  metal  sign,  must  approved  bushings  be  used? 

Yes.     (83 -e.) 

626.  Must  cut-outs,  transformers  for  low  wattage  lamps, 
flashers  and  similar  devices  be  in  a  weather-proof  and  access- 
ible compartment  when  built  in  the  sign ;  or  how  otherwise 
installed? 

Yes;  or  enclosed  in  a  separate  substantial  box  of 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   117 

metal  with  equivalent  thickness  of  the  sign  metal  and  access- 
ible.    (83 -b.) 

627.  When  may  wood  be  used  for  decoration  only  of 
electric  sign? 

When   kept   2    in.   from   nearest   lamp   receptacle. 
(83 -a.) 

628.  What  size  sheet  metal  must  be  used  for  electric 
signs? 

Not  less  than  No.  28  U.  S.  Gauge.     (83 -a.) 
620..  What  size  holes  are  required  for  drainage  in  the 
bottom  of  a  compartment? 

Not  less  than  1/4  in.  in  diameter.     (83 -b.) 

630.  Is  galvanized,  enameled,  or  three-coat  painted  metal 
acceptable  and  required? 

Yes,    as   approved   protection   against   corrosion   it 
will  be  acceptable.     (83 -a.) 

631.  In  metal  signs  (where  conduit,  cable,  or  metal  com- 
pletely encloses  conductor),  give  space  limit  for  receptacle 
terminals  from  each  other  and  from  sign  metal? 

One-half  inch.     (83-d.) 

632.  Must  receptacles  for  signs  be  of  special  design? 
Yes.     (83-d.) 

633.  How  must  receptacles  be  designed  and  placed? 

To  prevent  possible  turning  after  installation.     (83 -d.) 

634.  Are  wires  on  the  outside  of  electric  signs  (in  open 
work),    permitted      to    touch    metal?     What    is    surface 
distance? 

No.;  i  in.     (83-6.)     Read  624. 

635.  How  must  exposed  parts  of  wires  and  terminals  be 
treated? 

So  as  to  prevent  corrosion.     (83-6.) 

636.  Must  all  wires  be  soldered  to  terminals? 
Yes.     (83 -e.) 

637.  How  far  apart  must  open  wiring  for  signs  be  kept? 
Two  and  one -hah*  inches  up  to  300  volts;  4  in.  for 

higher  voltages.     (83-6.)     Read  621. 

638.  Where  open  work  is  not  permitted  by  general  Code 
conditions,  what  system  must  be  used  on  the  outside  of 
sign  structure? 

Approved  metal  conduit  or  approved  armored  cable. 
(83-e.) 


118       QUESTIONS  AND  ANSWERS  ON  THE 

639.  What  special  support  when  distances  are  more  th 

1  ft.  apart  and  less  than  2  ft.  apart  between  receptacles, 
is  required? 

Additional  insulator  preserving  the  required  spacing 
must  be  inserted.     (83-6.)     Read  621. 

640.  Is  approved  metal  conduit  or  armored  cable  satis- 
factory for  passing  leads  from  sign  to  outside? 

Yes.     (83-f.) 

641.  What  other  method  is  approved  for  conducting  wires 
from  signs  to  connect  with  supply  wires? 

Neatly  cabled  and  passed  through  one  or  more  ap- 
proved non -combustible,  non-absorptive  bushings.     (83-f.) 

642.  Is  any  size  less  than  No.  14  B.  &  S.  permitted  on 
signs? 

No.     (83-6.) 

643.  Must  double  braided  wire  always  be  used? 

Yes,  except  where  open  work  is  permitted,  see  ques- 
tion No.  622,  when  ordinary  type  is  acceptable.     (83 -f.) 

644.  May  single-pole  switches  be  used  for  control  of  out- 
door signs? 

No.     (24-0.) 


DECORATIVE  LIGHTING  SYSTEMS 


Christmas    tree  series  miniature  outfits  acceptabl 
April,  1912,  List  of  Fittings. 

645.  Is  special  permission  in  writing  necessary  from  the 
inspection   department   for   temporary   installation   of   so- 
called  decorative  lighting? 

Code  says  may  be  given.     (37-a.) 

646.  What  limitation  is  placed  by  the  National  Code 
upon  the  approval  of  decorative  lighting  systems  by  the 
inspection  department  having  jurisdiction? 

The  wires  of  any  circuit  shall  not  be  over  150  volts, 
and  no  group  of  lamps  requiring  more  than  1320  watts  shall 
be  dependent  on  one  cut-out.  (37-a.) 


ELECTRIC  HEATERS  FOR   GENERAL  USE 

647.  Is  an  approved  stand  for  flat  iron  and  similar  heat- 
ing appliances  obligatory? 

Yes.     (25-6.) 

648.  How  must  stationary  electric  heater  be  installed? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   119 

In  plain  sight  protected  by  a  cut-out,  controlled  by  a 
switch  (double  pole  when  over  660  watts),  plainly  showing 
when  current  is  on  or  off;  and  isolated  from  inflammable 
materials.  (25-a  and  b  and  f.) 

649.  May  electric  heaters  be  concealed? 

No,  except  by  special  permission  of  inspection  de- 
partment having  jurisdiction.  (25-b.) 

650.  Can  ordinary  flexible  cord  be  used  for  portable  heat- 
ing devices,  such  as  flat  irons  and  smoothing  irons,  consum- 
ing over  250  watts? 

No,  must  have  asbestos  fiber  covering  over  rubber  of 
cord  and  otherwise  as  under  Table  No.  14,  Section  9,  Flex- 
ible Cords.  (54-d-) 

651.  How  must  cords  or  cables  be  attached  to  heating 
apparatus? 

So  that  kinking  or  chafing  at  or  near  point  of  con- 
nection will  be  avoided.  (25  -d.) 

652.  How  must  a  flexible  conductor  for  heating  devices 
be  connected  to  the  circuit? 

By  an  approved  plug  device  pulling  out  in  case  of 
abnormal  strain  on  conductors.  (25 -d.) 

653.  How    must    radiators,    ranges,    plate    warmers    be 
treated? 

As  sources  of  heat  and  isolated  from  inflammable 
material.  (25 -f.) 

654.  Must  such  devices  be  provided  with  name  plates? 
Yes,  giving  the  maker's  name  and  normal  capacity 

in  volts  and  amperes.     (25  -g.) 

MERCURY  VAPOR   LAMPS,   HIGH  POTENTIAL, 
VACUUM   TUBE  SYSTEMS 

655.  How  must  the  high  potential  coils  and  regulating 
apparatus  be  installed? 

In  approved  steel  cabinets  not  less  than  i/io  in. 
thickness,  well  ventilated  and  constructed,  so  as  to  confine 
escaping  flame  or  sparks  in  case  of  burn-out  in  the  various 
coils.  (34-d.) 

656.  Is  it  necessary  to  mount  all  apparatus  in  steel  cab- 
inets on  a  slate  base? 

Yes.     (34-d.) 


120  OFFICIAL  NATIONAL  ELECTRICAL  CODE 

Grounding  of    Mercury  Vapor  Lamp    Systems — High  Po- 
tential. 

657.  Is  it  necessary  to  ground  the  steel  cabinet? 

Yes,  either  steel  cabinet  or  enclosing  case  of  appa- 
ratus must  both  be  grounded  on  positive  side.     (34-d.) 

Mercury  Vapor  Lamps — Enclosed. 

658.  What  requirements  govern  supply  conductors  lead- 
ing into  high  potential  case,  and  what   voltage  limitation 
applies? 

Standard  requirements  according  to  system  used  un- 
der low  potential  and  not  over  300  volts.     (34-d.) 

659.  What  is  the  maximum  number  of  mercury  vapor 
lamps  permitted  on  one  cut-out? 

Five,  when  contained  in  a  single  frame  and  lighted 
by  a  single  operation.     (34~a.) 

660.  Are  cut-outs  obligatory  for  each  lamp  or  series  of 
lamps? 

Yes.  (34-a.) 

66 1.  How  must  resistances  be  protected  when  exposed 
to  flying  lint  or  combustible  material? 

By  fine  wire  gauze  over  all  openings  through  casing. 
(34-b.) 

662.  Can  any  other  resistances  or  regulators  except  those 
enclosed  in  non-combustible  cases  be  used? 

No.  (34-d.) 


SECTION  SIX 

DIVISION  FIVE 
FIXTURES  AND  SOCKETS  AND  FLEXIBLE  CORDS 

Fixtures  in  General 

Canopies. 

Fixtures  in  Show  Cases. 

Fixtures — Wooden. 

Portable  Lamps. 

SOCKETS 

Double-ended  Sockets. 
Miniature  Candelabra. 
Water-proof  Sockets. 

FLEXIBLE   CORD,  THEATER   CABLES  AND 
ELEVATOR   CABLES 


121 


SECTION  SIX 

DIVISION  FIVE 

FIXTURES  AND  SOCKETS  AND  FLEXIBLE  CORDS 

[Limited  to  300  volts  maximum.     Below  10  volts,  no 
Code  requirements.] 

Fixtures  in  General. 

Following  questions  apply  to  fixtures  in  general,  except 
as  specifically  indicated.  References  are  principally  taken 
pom  Code  Class  "C"  Inside  Work  and  Code  Class  "D." 

663.  What  is  the  maximum  voltage  permitted  between 
conductors  in  the  same  fixtures? 

Three  hundred  volts.     (26-7.) 

664.  May  No.  18  fixture  wire  or  cord  which  has  a  carry- 
ing capacity  of  3  amperes,  be  protected  with  a  6-ampere 
fuse? 

Yes.     (23-e.) 

665.  What  is  the  limit  of  wattage  for  any  number  of 
lamps  on  one  cut-out,  whether  on  one  fixture  or  several? 

Six  hundred  and  sixty  watts.  Exception  in  case 
large  chandeliers  and  theater  wiring  by  inspection  department 
having  jurisdiction.  (23-d.) 

666.  What  is  the  smallest  size  wire  permitted  on  fixtures, 
either  solid  or  stranded? 

No.  18  B.  &  S.     (55-b.) 

667.  Can  ordinary  approved  No.  14  (type  letter  R.  S.) 
rubber-covered  wire  be  used  on  exposed  work  on  fixtures? 

Yes.     (ss-a.) 

668.  Can  fixtures  be  wired  with  any  kind  of  approved 
flexible  cord? 

Yes.     (55-a.) 

669.  Are  stranded  conductors  approved  for  fixture  work? 
Yes.     (55-b.     Also  54  a  to  c.) 

670.  Is  it  necessary  for  solid  fixture  wire  conductors  to  be 
"tinned"? 

Yes.     (55 -c,  and  50 -a.) 
123 


124       QUESTIONS  AND  ANSWERS  ON  THE 

671.  When  may  slow-burning  wire  be  used  on  fixtures? 
Where  wiring  is  exposed  to  over   120°  F.    (55-a.) 

See  also  No.  701. 

672.  What  test  is  sufficient  to  show  the  elasticity  of  the 
braid  required  on  fixture  wiring? 

Must  be  elastic  enough  to  stand  being  bent  around 
a  cylinder  twice  the  diameter  of  the  wire  without  injury  to 
the  braid.  (55-e.) 

673.  May  the  wires  of  two  systems  be  introduced  in  or  on 
the  same  fixture,  such  as  an  electrolier  fan  or  a  chandelier? 

No.     (26-y.) 

674.  Where  conductors  are  not  completely  enclosed  in 
metal,  as  on  chains  for  domes,  what  kind  of  wires  are  re- 
quired unless  pendant  (type  letter  "C")  or  portable  (type 
letter  "P ' ')  is  used? 

Stranded  rubber-covered;  insulation  not  less  than 
1/32  in.  thick  and  braided  (77-d.) 

675.  Where  supply  wires  enter  fixture  stems  or  casings, 
are  hickeys  or  similar  devices  protecting  wire  coverings 
approved? 

Yes,  must  be  used.     (77-d.) 

676.  How  must  straight  electric  fixtures  be  attached  when 
connected  on  a  concealed  knob  and  tube  job? 

To  a  7/8  in.  wooden  block  fastened  securely  between 
studs  and  floor  timbers  flush  with  back  of  the  laths  which 
must  be  large  enough  to  allow  boring  for  the  flexible  tubing 
to  enclose  each  wire. ,  and  properly  support  fixture. 

Or,  a  3/4  in.  wooden  block  must  be  placed  on  the 
plaster  side  of  the  laths  and  securely  screwed  thereto. 

(24-e.) 

677.  How  may  supply  wires  be  insulated  from  gas  pipes? 
Flexible  insulating  tubing  must  be  placed  over  wires 

from  last  knob  to  one  inch  beyond  outlet.     (26-u)  Read  304. 

678.  How  near  to  the  ceiling  or  walls  must  the  insulating 
joint  required  on  combination  or  otherwise  subject  to  ground 
fixtures  be  located? 

As  near  as  possible.     (3O-a.) 

679.  How  must  fixtures  supported  at  outlets  on  metallic 
protective  systems  or  from  any  gas  piping,  metal  lathing  or 
any  other  part  of  the  building,  grounded  or  liable  to  be 
grounded,  be  insulated? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   125 

By  approved  insulating  joint  as  close  as  possible  to 
celings  or  walls  of  the  building,     (ao-a.)    Read  No.  688. 

680.  Can  electric  gas  lighting  circuits  or  bell  wires  be 
installed  on  combination  fixtures? 

Frictional  system  only.     (87-a.) 

68 1.  How  must  gas  pipes  be  treated  above  the  insulating 
joint? 

By  approved  flexible  tubing  over  pipe,     (ao-a.) 

682.  How  must  outlet  tubings  be  secured? 

So  that  they  will  not  be  pushed  back  when  canopy  is 
in  place.  (30 -a.) 

683.  Is  it  necessary  for  fixtures  to  be  of  water-tight  con- 
struction when  installed  out  of  doors? 

Yes.     (30-b.) 

684.  Are  fixtures  wired  on  the  outside  approved  for  use  in 
show   windows   or  in   vicinity   of   especially  inflammable 
material? 

No.     (30-0.) 

685.  May  fixtures  be  installed  that  contain  short  circuits 
between   conductors;   or   contact   between   conductor   and 
metal  or  fixtures?     (So-called  "grounded  fixtures.)" 

No.     (ao-d.) 

686.  Must  fixture  arms  be  secured  with  a  set  screw  or 
otherwise  in  addition  to  being  screwed  in  the  body  of  the 
fixture? 

Must  be  reliably  secured  to  prevent  turning.     (77-b.) 

687.  What  other  methods  may  be  used,  instead  of  set 
screws,  to  secure  arms  to  fixture  body? 

May  be  soldered  or  cemented.     (77-b.) 

688.  When     may     insulating     joints     be    omitted    on 
fixtures    supported    at    outlets    on    metallic    protective 

system? 

When  the  insulation  of  the  wiring  in  the  straight 
electric  fixture  is  equal  to  the  insulation  of  its  circuit; 
and  the  receptacle,  socket,  or  wireless  cluster  are  approved. 
(30-a.)  Read  679. 

689.  Are  insulating  joints  with  soft  rubber  in  their  con- 
struction approved? 

No,  fine  print  note.     (76-3.) 

690.  How  many  threads  must  engage  on  screw  joints  of 
arms? 


126        QUESTIONS  AND  ANSWERS  ON  THE 


At  least  five.     (77-b.) 

691.  May  any  other  methods  than  screw  joints  be  used, 
such  as  brazing  and  soldering? 

Only  when  ample  strength  and  durability  is  secured. 
(77-b.) 

692.  Must  all  sockets  used  on  fixtures  be  permanently 
attached  to  the  metal? 

Yes.     (77-c.) 

693.  When  may  receptacles  having  exposed  terminals  be 
used  on  fixtures? 

Only  when  completely  enclosed  in  metal,  such  as  a 
box.     (77-c.) 

694.  Is  the  filing  or  removal  otherwise  of  burrs,  fins  and 
sharp  edges  required  on  fixtures? 

Must  invariably  be  modified  or  removed  so  that  wires 
drawn  over  them  will  not  be  injured.     (77 -d.) 

695.  In  wire  ways  on  fixture  stems  and  similar  places,  is  it 
required  that  wires  or  flexible  cord  can  be  drawn  in  without 
injury? 

Yes.     (77-d.) 

Canopies. 

696.  Can  cut-outs  or  fuses  of  any  kind  be  placed  in 
opies  or  shells  of  fixtures? 

No.     (23-c.) 

697.  When    fixtures   arrive   from   factory    with   insuffi- 
ciently large  shells  and  where  canopies  and  outlet  boxes  are 
too  small  for  proper  installation  of  necessary  splices,  what 
must  be  done? 

They  must  be  changed  to  provide   enough  room. 

(26-W.) 

698.  If  a  fixture  is  attached  to  a  wooden  ceiling  or  to  a 
block  on  wood  lathed  and  plastered  ceiling  is  a  canopy  insu- 
lator required? 

No.  (so-a.)     Read  679,  688,  699. 

699.  Is  it  necessary  to  insulate  all  fixture  canopies  from 
wall  or  ceiling  where  insulating  joints  are  required? 

Yes.     (30-a.)     Read  688. 

700.  When  may  flat  canopies,  tops  or  backs,  be  used  or 
fixtures? 

Only  when  installed  on  outlet  boxes.     (3O-a.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    127 

Show  Case  Fixtures. 

701.  When  wiring  for  show  case  fixtures,   ceiling  bull's 
eye,  such  as  used  in  theaters,  and  similar  fixtures  where 
lamps  are  so  enclosed  as  to  cause  great  heat,  is  slow  burn- 
ing wire  approved? 

Yes,  if  temperature  is  in  excess  of  120°  F.  (49 
degrees  Centigrade).  (26-v.) 

702.  Is  it  required  that  such  forms  of  fixtures  be  sub- 
mitted for  examination,  tests  and  approval  to  the  inspection 
department  having  jurisdiction  before  being  introduced  to 
use,    unless    already    approved   by   Underwriters'    Labora- 
tory? 

Yes.     (26-v.) 

703.  Does  the  Code  require  that  supply  conductors  and 
fixtures,  and  especially  splices,  be  kept  from  contact  with 
grounded  part  of  gas  pipes? 

Yes.     (26-w.) 

Wooden  Fixtures. 

704.  Are  hard  wood,  or  hardwood  and  metal,  fixtures  ap- 
proved, and  under  what  condition? 

Yes,  where  requisite  mechanical  strength  is  secured 
of  a  metal  fixture  same  size  and  form.  (77 -a.) 

705.  On  wooden  fixtures,  is  it  necessary  to  use  armored 
conductors  and  proper  fittings  upon  all  the  wood  parts? 

Yes.     (77-d.)     See  also  No.  706. 

706.  What  must  be  done  in  non-metallic  fixtures  if  arm- 
'ored  approved  conductors  are  not  used? 

Metal  wire -ways  must  be  used,  or  they  must  be  metal 
lined.  (77-d.) 

Portable  Lamps. 

707.  When    must    wire    guards    be    used    on    portable 
lamps? 

Whenever  necessary  to  prevent  contact  with  inflam- 
mable material  or  protect  from  breakage.  (32 -d.) 

708.  What  kinds  of  portable  cord  may  be  used  with  port- 
ables? 

Type  letters  "P" ;  "P.  Wp. ;  and  P.  O.,  according  to 
conditions  as  outlined  in  Tables  Nos.  u,  12,  13,  Section  9." 
Type  letter  P.  A.  is  also  permitted. 


128       QUESTIONS  AND  ANSWERS  ON  THE 
SOCKETS 

709.  How  must  sockets  be  installed  where  inflammable 
gases  or  injurious  vapors  exist? 

Socket  and  incandescent  lamp  must  be  enclosed  in  a 
vapor-tight  globe  supported  on  pipe  hanger  and  wired  with 
approved  rubber -covered  wire  soldered  directly  to  circuit. 
(3 1 -a.) 

710.  Are   key   sockets  forbidden  over  inflammable  stuff 
or  when  exposed  to  flying  or  combustible  material? 

Yes.     (si-c.) 

711.  What  size  wire  must  a  socket  be  able  to  securely 
grip? 

No.  16  or  18  B.  &  S.     (72-h.) 

712.  How  must  standard  key  sockets  be  rated? 

The  standard  key  sockets  (screw  shell,  standard  Edi- 
son and  ordinary  "slow  make"  switch),  250  watts,  250  volts. 
(72-b.) 

713.  Must  sockets  be  marked  with  manufacturer's  name 
and  rating  of  socket? 

Yes.     (72-a.) 

714.  What  is  amperage  limit  allowed  for  a  standard  key 
or  pull  socket? 

Two  and  one -half  amperes.     (72-b.) 

715.  Does  a  key  socket  with  standard  Edison  shell  and 
special  switch  which  makes  and  breaks  with  a  quick  snap, 
and  does  not  stop  when  motion  has  once  been  started  by 
handle  or  button,  take  a  higher  rating  than  a  250  watt,  250 
volt,  key  socket? 

Yes,  rating  660  watts,  250  volts.     (72-b.) 

716.  How  are  standard  keyless  sockets  rated? 
Standard  keyless  sockets,  Edison  screw  shell,   660 

watts,  250  volts.     (72-b.) 

717.  What  is  limitation  on  any  voltage  on  a  keyk 
socket? 

Six  amperes.     (72-b.) 

718.  Are  sockets  with  an  inlet  for  3/8-in.  pipe,  used 
pendants,  acceptable? 

Yes,  with  reinforced  cord.     (72-e,  fine  print  note.) 

719.  Are  smooth  holed  inlet  insulating  bushings  necessarj 
for  sockets,  and  what  size  hole  should  they  have? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   129 

Yes,  at  least  9/32  for  ordinary  flexible  cord  drop; 
larger  for  reinforced  cord.  (72 -q.  and  fine  print  note.) 

720.  Is  it  obligatory  for  socket  to  firmly  hold  lamp  in 
place? 

Yes.     (72-1.) 

721.  Is  a  contact  sufficient  to  prevent  undue  heating 
with  device  in  place  and  maximum  current  obligatory? 

Yes.     (72-i.) 

722.  Must  socket  bases'  on  which  current-carrying  parts 
are  mounted  be  of  porcelain? 

Yes.     (72-j.) 

723.  Is  it  obligatory  that  current  carrying  parts  of  socket 
be  protected  from  contact  or  liability  of  contact  with  other 
objects  than  as  intended? 

Yes.  (72-1.)  Example:  Sockets  hung  with  pro- 
tecting shells  omitted. 

724.  What  heat  test  is  approved  for  the  material  of  a 
socket  key  handle? 

That  it  will  not  soften  in  a  70°  F.  (21°  C.)  ah-,  with 
the  heat  of  a  50  candle-power  (carbon)  lamp  inserted. 
(72-k.) 

725.  Is  sealing  by  water-proof  compound   necessary  for 
holding   screws   of   sockets  in   porcelain   pieces?    what   is 
its  melting-point? 

Yes;  200°  F.,  93°  C.     (72-!.) 

726.  Are  porcelain,  mica,  and  similar  insulated  materials, 
properly  constructed,  acceptable  for  all  parts  of  sockets? 

Yes,  if  strong  and  durable  and  not  applied  where 
subject  to  hard  usage.  (72-p  and  fine  print  note.) 

Double  Ended  Sockets. 

727.  Are  double  ended  sockets  allowed  a  higher  rating  or 
amperage  than  single  sockets? 

Each  end  is  rated  250  watts,  250  volts,  for  key 
sockets ;  660  watts,  250  volts  for  keyless  sockets. 

Only  21/2  amperes  per  key  socket  or  6  for  keyless 
sockets  is  permitted.     (72 -b.) 
Miniature  and  Candelabra. 

728.  How    are    miniature    and    candelabra    key    sockets 
rated? 

Seventy -five  watts,  125  volts.     (72 -b.) 


130       QUESTIONS  AND  ANSWERS  ON  THE 

Water-proof  Sockets. 

729.  How  must  weather-proof  drops  be  installed  in  damp 
places? 

Weather-proof  sockets  suspended  by  separate  strand- 
ed rubber-covered  wires  not  smaller  than  No.  14  B.  &  S. 
gauge,  (ai-b.)  Read  732. 

730.  When  pendant  is  over  3  ft.  long,  what  recommenda- 
tion is  made  for  wires  in  damp  or  wet  places? 

That  they  be  twisted  together.     (3i-b.) 

731.  How  must  weather-proof  drops   be  connected  to 
the  circuit  wires? 

Soldered  direct  to  them,  but  supported  independ- 
ently of  them.  (3i-b.) 

732.  What    is    rating    for    weather-proof    sockets    with 
standard  Edison  shells  and  no  exposed  carrying  parts? 

Six  hundred  and  sixty  watts,  600  volts.     (72-b.) 

FLEXIBLE  CORD  AND  THEATER  AND  BORDER  AND 
ELECTRIC  LIGHTING  AND  CONTROL  CABLES 

Limit  300  volts  maximum 

For  details  see  Tables  10,  11,  12,  13,  15,  16,  17,  Section 
Nine.  (Code  Class  D,  Rule  54)  References  also  Code  Class 
C,  Rule  32. 

733.  Where  may  type  C  flexible  cord  be  used? 

Only  for  pendants,  "drop  lights"  wiring  of  fixtures. 
(32-d.) 

734.  What  kind  of  cord  must  be  used  for  portable  lamps 
or  motors? 

Type  letters  "P"  or  "P.  Wp."  See  tables  n  and  12, 
Section  Nine ;  or  heavier  insulations  per  conditions,  accord- 
ing to  tables  given. 

735-  What  kind  of  cord  is  the  only  kind  permitted  in 
show  cases  or  show  windows? 

Cord  having  approved  metal  armor.  Type  letter 
P-A.  (32-6.)  Exception  at  temperature  of  120°  F.  Read 
701. 

736.  May  flexible  cord  be  used  on  systems  of  over  300 
volts? 

No,  except  on  street  railway  property.     (32-b.) 

737.  Is  so-called    "commercial  cord,"  of  insulation  and 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   131 

make  up  less  than  described  in  the  tables,  Section  Nine, 
approved? 

No.     (3 2 -a  and  54 -a  and  b.) 

738.  How  must  flexible  cord  be  installed  in  the  socket  or 
rosette  on  all  kinds  of  drops? 

Entire  weight  of  socket  and  lamp  upon  the  flexible 
cord  must  be  borne  by  an  approved  method,  such  as  a  knot 
under  the  bushing  in  the  socket;  a  similar  arrangement 
must  be  made  at  top  in  the  rosette.  (32-g.) 

739.  What  type  of  cord  is  approved  for  pendant  lamps 
provided  with  long  cords? 

Type  letter  P.     (54-c-i.) 

740.  Define  conditions  and  insulation  required,  also  sizes 
for  the  various  applications  of  flexible  cord? 

See  Tables  hi  Section  Nine. 

741.  Give  smallest  size  conductor  allowed  in  making  up 
the  strands  of  an  elevator  control  cable.     (Type  letter  E.) 

Sixteen  B.  &  S.  (54 -g.)  See  also  Table  17,  Section 
Nine. 

742.  Define  conditions  of  use  and  insulation  required,  and 
sizes  of  conductors  for  theater,  and  elevator  lighting  and 
control  cables? 

See  Tables,  Section  Nine. 

743.  Is  ordinary  flexible  cord  allowed  where  drop  lights 
(pendants)  may  come  in  contact  with  surrounding  objects? 

All  flexibles  described  under  tables  in  Section  9,  ex- 
cept C  and  Cw.p  are  acceptable.  (54-c-i.) 

744.  When  must  flexible  wires  or  cables  be  used  instead  of 
any  of  the  various  type  letter  kinds  (see  tables,  Section  9) 
of  flexible  cord? 

Whenever  service  is  too  severe  for  then*  insulation 
durability.  (32-d.)  Example :  Long  extension  cords  in 
packing  houses. 

745.  May  flexible  cord  of  any  type  or  kind  be  used  to 
supply  lamps  or  other  devices,  when  used  instead  of  wire 
installation  even  if  supported  on  knobs? 

No. 


SECTION  SIX 

DIVISION  SIX 

ELECTRIC   CRANES 
IN  GENERAL 

Switches  and  Cut-outs. 

Controllers. 

Motor  Grounding. 


133 


SECTION  SIX 
DIVISION  SIX 

ELECTRIC  CRANES 
IN  GENERAL 

Questions  under  Section  Six,  Code  Class  "C,"  also  apply 
in  general,  except  where  modified  by  the  following: 

746.  How  must  wiring  for  apparatus,  etc.,  be  installed, 
generally  speaking,  when  not  covered  by  the  questions  fol- 
lowing this  number? 

Must  comply  with  the  general  requirements  for  its 
class  and  voltage.  (43,  italics,  under  Electric  Cranes.) 

747.  What  kind  of  insulation  must  be  used  on  conductors 
between  resistances  and  contact  plates  of  rheostats? 

Rubber,  where  exposed  to  moisture  and  an  insula- 
tion is  necessary;  and  where  they  are  grouped.  (43-3-1 
and  d.)  See  749. 

748.  Is  slow-burning  wire  ever  required? 

Yes,  where  subject  to  severe  external  heat.  (43- 
a-i.) 

749.  What  kind  of  wire  is  excepted  under  Question  747? 
Bare  collector  wires,  those  between  resistances  and 

contact  plates  of  rheostats,  and  those  subjected  to  severe 
external  heat.     (43-a-i  and  d.) 

750.  What  is  the  smallest  size  wire  acceptable  in  use  on 
electric  cranes? 

No.  12  B.  &  S.     (43-a-i.) 

751.  How  must  wires  other  than  collector  wires  be  in- 
stalled? 

Per  free  air  system  (Section  6,  Division  i)  or  metallic 
conduit  system  (Section  6,  Division  2).  In  dry  places  where 
distance  between  wires  required  for  open  work  cannot  be 
secured,  (see  Nos.  249,  285.)  approved  flexible  tubing  (non- 
metallic)  encasing  each  wire  and  securely  fastened  will  be 
accepted.  (43-3-2.) 

752.  At  all  times,  how  far  must  collector  wires  be  kept 
from  the  surface  wired  over? 

One  and  one-half  inch.     (43-3-2.) 
135 


J 


136       QUESTIONS  AND  ANSWERS  ON  THE 

753.  How  must  collector  wires  be  held  at  ends? 
By  approved  strain  insulators.     (43 -a -2.) 

754.  How  often  must  collector  wires  be  supported  aloi 
run  ways,  unless  span  is  over  20  ft.? 

Every  20  ft.     (43-a-3.) 

755.  What  must  be  done  when  span  is  over  20  ft.,  and 
what  is  the  limit? 

Distance  must  be  increased  in  the  same  proportion; 
in  no  case  shall  span  exceed  40  ft.     (43 -£-3.) 

756.  How  far  must  collector  wires  be  separated  when  rui 
in  a  horizontal  plane? 

At  least  6  in.     (43-a-3«) 

757.  When  not  run  in  a  horizontal  plane,  what  se] 
tion  must  be  observed? 

Eight  inches.     (43-a-3«) 

758.  Where  bridge  collector  wires  are  over  80  ft.  long, 
how  often  must  insulating  supports  (upon  which  wires  may 
lie  loose)  be  provided? 

At  least  every  50  ft.     (43 -a -4.) 

759.  What  is  the  least  spacing  between  bridge  collector 
wires  allowed? 

Two  and  one -half  inches;  recommended  that  greater 
spacing  be  used  whenever  possible.     (43-3-4.) 

760.  What  are  the  minimum  sizes  for  collector  wires  ac- 
cording to  the  distance  between  rigid  supports? 

"Distance  between  Size  wire 

rigid  supports  required 

Feet  B.  &  S. 

o  to  30  6 

31  to  60  4 

Over  60  «  2 

(43 -a -50 

761.  How  must  collectors  be  designed  with  reference  to 
sparking? 

So  that  it  will  be  reduced  to  a  minimum.     (43 -b.) 

Switches  and  Cut-outs. 

762.  Can  one  main  switch  be  used  for  all  motors  of  an  j 
electric  crane? 

Yes.     (Italics,  43.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    137 

763.  Is  a  cut-out  and  switch  necessary  for  the  main  col- 
lector wires,  and  how  must  it  be  located? 

Yes;  located  easy  of  access  from  floor.     (43-0-1.) 

764.  Is  a  cut-out  and  a  switch  necessary  for  leads  from 
main  collector  wire  on  electric  cranes  operated  from  cabs; 
and  where  must  they  be  located? 

Yes;  readily  accessible  to  operator.     (43-0-2.) 

765.  Is  it  necessary  to  use  a  cut-out  for  each  motor  of  a 
single  crane? 

Yes,  each  motor  lead  must  be  protected  by  a  cut-out ; 
locate  in  cab  if  used.     (43-0-3.) 

Controllers. 

766.  Where  electric  crane  is  outdoors,  what  kind  of  in- 
sulation is  required  between  resistances  and  contact  plates 
of  rheostats? 

Rubber-covered,    type    letters   R.    S.,    according    to 
voltage.     (43-d.)     See  tables  on  wires,  Section  9. 

767.  Where  wires  are  grouped  in  outside  controller,  what 
kind  of  insulation  must  be  used? 

Rubber-covered.     (43 -d.) 

768.  How  must  resistances  be  treated  where  crane  oper- 
ates over  readily  combustible  material,  such  as  gunpowder 
or  lint? 

Resistances  must  be   enclosed   in  non-combustible 
material,  such  as  asbestos  board.     (43-d.) 

769.  If  resistances  are  in  a  cab,  how  far  above  the  top 
of  such  resistance  is  a  non-combustible  enclosure  required? 

From  floor  to  6  in.  above  the  top  of  the  resistances. 
(43-d.) 

Motor  Grounding. 

770.  Is  it  necessary  for  motor-frame  trucks  and  the  entire 
frame  of  the  crane  to  be  grounded? 

Yes.     (43-e.) 


SECTION  SEVEN 

ELECTRIC  RAILWAY  SYSTEMS 

Railway  Feed  Wires. 
Trolley  Wires. 

CAR  WIRING  AND  EQUIPMENT  OF  CARS 

Protection  of  Carbody. 

Wires,  Cables,  Etc. 

Cut-outs,  Circuit -breakers  and  Switches. 

Conduit. 

Moulding. 

Lighting  and  Lighting  Circuits. 

Heaters  and  Heating  Circuits. 

Air-pump  Motor  and  Circuits. 

Main  Motor  Circuits  and  Devices. 

GENERAL  RULES 
Grounded  Trolley  Circuits 

Flexible  Cord. 


139 


SECTION  SEVEN 

ELECTRIC  RAILWAY  SYSTEMS 

Following  questions  apply  upon  Electric  Railway  systems 
as  indicated.  References  are  taken  principally  from  Code 
Class  B,  Rule  12,  and  Code  Class  C,  Rules  40  to  42  inclusive, 
Outside  and  Inside  Work,  respectively. 

Railway  Feed  Wires. 

771.  How  must  feed  wires  upon  railway  power  plants 
before  leaving  power  plant  be  protected? 

"Each  feed  wire  must  have  approved  automatic 
circuit-breaker  or  other  device  which  will  immediately  cut 
off  the  current  in  case  of  an  accidental  ground.  Device  must 
be  mounted  on  fire -proof  base  and  in  full  view  and  in  reach 
of  the  attendant."  (9 -a.)  Read  776. 

Trolley  Wires. 

772.  What   are   smallest   sized   trolley    wires   permitted 
under  the  National  Code? 

No.  o  B.  &  S.  Copper  or  No.  4  B.  &  S.  silicon  bronze. 
f(i2-L) 

773.  Does  the  Code  require  that  trolley  wires  readily 
stand  the  strain  put  upon  them  when  in  use? 

Yes.     (i2-i.) 

774.  How  many  insulations  must  trolley  wire  have  from 
the  ground? 

Double  insulation,  wooden  pole  being  considered  as 
one  insulation.  (i2-j.) 

775.  How  must  trolley  wires  be  divided? 

Into  sections,  so  that  in  case  of  fire,  current  may  be 
shut  off  from  the  particular  section  and  not  interfere  with 
firemen.  (i2-k.) 

776.  Does  the  last  requirement  apply  also  to  feeders? 
Yes.     (i2-k.) 

777.  Is  it  obligatory  to  protect  against  accidental  contact 
when  crossed  by  other  conductors? 

Yes.     (12-1.) 

778.  How  must  guard  wires  be  insulated  and  treated? 

141 


142       QUESTIONS  AND  ANSWERS  ON  THE 

Insulated  from  ground  and  electrically  disconnected 
in  not  more  than  300 -ft.  sections.  (12-!.) 

779.  What  requirement  exists  upon  ground  return  wires, 
for  the  diminution  of  electrolytic  corrosion  of  underground 
metal  work? 

Ground  return  wires  must  be  arranged  so  that 
potential  difference  between  grounded  dynamo  terminal  and 
any  point  on  the  return  circuit  will  not  exceed  25  volts. 
(i2-m.) 

"It  is  suggested  that  the  positive  pole  of  the  dynamo  be 
connected  to  the  trolley  line,  and  that  whenever  pipes  or 
other  underground  metal  work  are  found  to  be  electrically 
positive  to  the  rails  or  surrounding  earth,  that  they  be  con- 
nected by  conductors  arranged  so  as  to  prevent  as.  far  as  possible 
current  flow  from  the  pipes  into  the  ground."  Fine  Print  Note. 
(12-m.) 

CAR  WIRING  AND  EQUIPMENT  OF  CARS 

Protection  of  Car  Body. 

780.  What    protection    is   required  over  all  wires   and 
parts  of  the  electrical  equipment  in  car  bodies  and  what 
exception  is  especially  made? 

One -eighth  of  an  inch  approved  fire -resisting,  in- 
sulating material,  or  sheet  iron  or  steel  not  less  than  4/100 
inch  thickness.  Motors  75  h.  p.  or  less  and  wires  carry- 
ing not  over  25  amperes  when  encased  hi  metal  conduit, 
excepted.  (40 -a -i.) 

781.  How  far  must  protection  above  required  extend  over 
motors  75  h.  p.  each? 

Eight  inches  beyond  all  edges  of  openings  on  motors. 
(40-a-2.) 

782.  How  far   must   the   protection  required   above  in 
Question  No.  780  extend  beyond  edges  of  motor  leads? 

Six  inches  on  all  sides.     (4O-a-2.) 

783.  How  far  must  protection  extend  beyond  edges  of 
all  devices  (unless  amply  protected  by  their  casing)  over 
resistances,     contactors,     arresters,     and    other    electrical 
apparatus  of  similar  kind? 

Eight  inches.     (40 -a -3.) 

784.  When   must   conductors   be   protected   by   a   6-in. 
extension   of   the   protection    (see   Question   No.    780)  on 
either  side? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   143 

When  designed  to  carry  over  25  amperes,  unless 
conduited  with  a  half-inch  air  space  between  conduit  and 
car.  (40-a-4.) 

785.  When    may   the    protection   specified   in    question 
No.  780  be  omitted  over  cables? 

When  flame-proof  outer  covering  of  1/8  in.  is 
provided  entire  length  of  cable;  also  provided  that  it  shall  be 
thoroughly  taped  or  sewed  at  the  ends,  where  taps  are  made, 
and  where  it  enters  apparatus.  (40-3-4.) 

786.  How  must  fire-proof  material  or  sheet  iron  or  steel 
be  treated  in  car  bodies? 

Must  have  joints  well  fitted;  securely  fastened  to 
sills,  floor  timbers  and  cross  braces;  and  have  entire  surface 
treated  with  water-proof  paint.  (40-3-5.) 

787.  What  material  is  required  for  cut-out  and  switch 
cabinets? 

Substantially  made  hardwood,  lined  with  fire -resist- 
ing insulating  material  securely  fastened  to  the  woodwork. 
After  material  is  in  place,  inside  of  cabinet  must  be  treated 
with  a  water-proof  paint.  (40-3-6.) 

Note  No.  43:    Metal  boxes  not  code. 

Wires,  Cables,  Etc. 

Wires  laid  (not  drawn)  in  conduit  may  be  R.  S.  type. 
(4o-b-3.) 

788.  What  is  the  minimum  size  for  motor,  trolley  and 
resistance  leads? 

No.  7  B.  &  S.     (4o-b-i.) 

789.  Give  minimum  size  conductor  for  heater  circuits? 
No.  12  B.  &  S.     (4o-b-i.) 

790.  Give  minimum  size  for  lighting  and  similar  auxili- 
ary circuit?? 

No.  14  B.  &  S.  gauge.     (4o-b-i.) 

791.  How   is    the    safe    carrying    capacity    of    motor, 
trolley  and  resistance  lead  wires  or  conductors   to  be  de- 
termined? 

"The  current  used  in  determining  the  size  of  motor, 
trolley  and  resistance  leads  shall  be  the  per  cent,  of  the  full 
load  current,  based  on  one  hour's  run  of  the  motor,  as  given 
by  the  following  table  : 


144       QUESTIONS  AND  ANSWERS  ON  THE 


Size  each  inotor 

Motor  leads 

Trolley  leads 

Resistance 
leads 

75  h   p   or  less 

50  per  cent. 

40  per  cent 

Over  75  h.  p  

45  per  cent. 

35  per  cent. 

15  per  cent. 

792.  May  approved  fixture  wire  be  used   on  approved 
clusters? 

Yes.     (4o-b-i.) 

793.  When  not  in  conduit  or  approved  moulding,  or  in 
cables  with  1/8  in.  enclosing  flame-proof  covers,  is  a  special 
rubber-covered  wire  required? 

Yes.  (40 -b -4.)  Exception:  When  motors  are  en- 
closed so  that  flame  cannot  extend  outside  of  casing,  flame- 
proof covering  is  not  required  on  motor  leads.  (40-5-4.) 

794.  What  sort  of  joints  need  not  be  soldered? 

Those  with  approved  splicing  devices,  and  those  con- 
necting leads  at  motors,  plows  or  third -rail  shoes.  (40-5-5.) 

795.  How  must  cable  connections  over  25  amperes  be 
made  (controller  connection  boards  excepted)  when  applied 
to  cut-outs,  switches  and  fittings? 

Lugs  or  terminals  must  be  soldered  to  the  cable  and 
securely  fastened  to  the  device  by  screws,  bolts  or  clamping. 
(4o-b-6.) 

Or,  end  of  cable  dipped  in  solder,  and  fastened  with 
at  least  two  sets  of  screws  with  check  nuts.  (40 -b -6.) 

796.  When  designed  to  carry  less  than  25  amperes,  how 
must  connections  of  conductors  to  fittings  be  made? 

Device  must  be  provided  with  up  turned  lugs  that 
will  grip  the  conductor  between  screw  and  lug,  screws  having 
flat  washers. 

Or,  by  dipping  ends  of  conductors  in  solder  and  ap- 
plying to  block  terminal  with  two  set  screws.  (4O-b-6.) 

Code  recommends  soldering  hi  addition  "to  binding 
screw  fastenings.  (40 -b -6.) 

797.  When   does  the  Code    Rule   40-b-6   for   car  wiring 
of    cable    connections,    soldering,    etc.,    apply?     See    Nos. 
795-796. 

On  circuits  of  over  25  volts,  and  over  5  amperes. 
(4o-b-6.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    145 

Cut-outs,  Circuit-breakers  and  Switches. 

798.  Is  it  necessary  to  enclose  switches,  such  as  knife 
switches,  and  cut-outs  with  exposed  metal  parts? 

Yes.     (40 -c -i.) 

799.  Is  it   necessary  for   switches   and   cut-outs  to   be 
mounted   on  insulating  non-combustible  material,  such  as 
fiber  or  asbestos,  when  not  enclosed  in  iron  or  steel  boxes? 

Yes.     (40 -c- 1.) 

800.  Is  it    necessary  for  a  switch    or  cut-out  base  to 
project  on  all  sides,  and  how  much? 

Yes,  1/2  in.     (40-0-1.) 

80 1.  What  kind  of  cut-outs  are  required? 

Approved  cartridge  or  approved   "blow-out"   type. 
(40-0-2.) 

802.  Are  single  pole  quick  break  or  approved  magnetic 
blow-out  switches  required  for  over  5  amperes  circuit? 

Yes.     (40-0-3.) 

803.  Are  snap,   double  break,  and  single  pole  switches 
accepted  for  5  amperes  or  less  capacity  circuits? 

Yes.     (40-0-3.) 

804.  Must  circuit-breakers  be  of  approved  type? 
Yes.     (40-0-4.) 

805.  Is  it  forbidden  to  fuse  circuits  above  safe  carrying 
capacity? 

Yes.     (40-0-5.) 

806.  Is  a  cut-out  required  near  the  current  collector  for 
cutting  off  all  current? 

Yes.     (40-0-6.) 

807.  When  a  metallic  return  circuit  is  used,  will  circuit- 
breakers  alone,  without  fuses,  be  sufficient? 

Yes,  when    circuit-breakers  are  connected  to  both 
sides  of  the  circuit.     (40-0-6.) 
Conduits. 

808.  What  particularly  small  size  conduit  is  acceptable 
for  lighting  circuits? 

Five -sixteenths  inch  internal  diameter,  and  1/2  in. 
external  diameter.     (4O-d-i.) 

809.  What  small  size  conduit  for  heating  and  air  motor 
circuits  may  be  used? 

Three-eighths  inch  internal  diameter  and  9/16  in. 
external  diameter.     (4O-d-i.) 
10 


146        QUESTIONS  AND  ANSWERS  ON  THE 

810.  Where   conduits   are   exposed   to   dampness,    what 
must  be  done? 

Must  be  made  water-tight.     (4o-d-i.) 

8 1 1.  How  must  conduits  be  treated  in  reference  to  con- 
tinuity,  entrance  of  junction  boxes  and  fittings,   and  in 
general? 

In  accordance  with  conduit  systems  in  general  under 
metallic  protective  systems.  See  Question  No.  321.  (40 
d-2-3-4-5.)  Exceptions  per  812  and  838. 

812.  Must  conduit  be  grounded  enclosing  conductors  con- 
necting between  third-rail  shoes  on  same  track? 

No,  must  be  insulated,     (4O-d-4  and  4o-i-2.) 

813.  Where    must   all  conduit   outlets  or  junction  box 
fittings  be  substantially  fastened? 

To  framework  of  car.     (4o-d-6.) 

Moulding. 

814.  Is  hardwood  moulding  permitted  where  circuits  are 
normally  not  exposed  to  moisture? 

Yes.     (40-6-1.) 

815.  What  is  the  special  construction  required  for  the 
fire-resisting  and  insulated  moulding  approved  for  use? 

Backing  not  less  than  1/4  in.  thick;  backing  must 
extend  i  in.  beyond  conductor  at  sides;  capping  1/8  in. 
thick  and  3/4  in.  extension  beyond  conductors;  joints  close. 
(4o-e-2.) 

8 1 6.  Must  joints  be  mitered? 
Yes.     (40-6-2.) 

817.  Are  either  screws  or  nails  acceptable  for  fastening 
moulding  in  place? 

Yes.     (40-6-2.) 

8 1 8.  Are  two  water-proof  paint  coatings  required,  both 
inside  and  out,  on  all  mouldings? 

Yes.     (40-6-2  and  40-6-3.) 

819.  Can    the    backings    be    omitted   from    fire-resisting 
moulding  when  the  surface  on  which  it  is  placed  is  at  least 
1/8  in.  insulating  material? 

Yes.   (40-6-2.) 

820.  Are  screws  required  for  the  backing  and  capping 
wooden  moulding? 

Yes.     (40-6-3.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   147 

Lighting  and  Lighting  Circuits. 

821.  What  is  the  wattage  limit  for  each  individual  lamp 
•used? 

One  hundred  and  twenty -eight  watts.     (40-f-i.) 

822.  Are  approved  receptacles  or  clusters  required  at 
outlets? 

Yes.     (40-f-i.) 

823.  How  must  circuits  be  run? 

In  approved  conduit  or  approved  moulding.     (4O-f-2.) 

824.  How  must  receptacles  be  fastened  on  a  metal  con- 
duit system? 

To  inside  of  the  conduit  box.  (40 -f -4.)  Exception : 
sign  lights.  (40 -£-3.) 

825.  Is  an  insulating  bushing  necessary  around  the  open- 
ing in  a  conduit  box  cover  for  a  lamp? 

Yes.     (4o-f-4.) 

826.  How  must  clusters  be  insulated  from  the  metal  con- 
duit? 

By  a  block  of  hard  wood  or  fiber  or  other  fire -resist- 
ing and  insulating  material.  (40 -f -4.) 

827.  When  wooden  moulding  is  used,  how  must  either 
receptacles  or  clusters  be  mounted? 

See  Question  No.  826.     (4O-f-5.) 

Heaters  and  Heating  Circuits. 

828.  Must  heaters  be  approved  type? 
Yes.     (40-g-i.) 

829.  How  far  from  all  woodwork  must  the  current-carry- 
ing part  of  panel  heaters  come? 

Four  inches.     (4o-g-2.) 

830.  How  far  must  current-carrying  parts  of  heaters  for 
cross  seats  be  located  below  the  under  side  of  the  seat? 

Six  inches,  unless  i  /4  in.  fire  lining  is  used  (as  defined 
in  Question  No.  780).  In  this  case,  distance  may  be  reduced 
to  3  in.  (40-g-2.) 

831.  Are  truss  plank  heaters,  mounted  on  1/4  in.  fire 
lining,  with  an  air  space  of  not  less  than  1/2  in.  between 
'back  of  heater  and  insulating  material,  approved? 

Yes.     (40-g-2.) 

832.  When  may  knob  and  tube  work  be  done? 

When  an  air  space  of  not  less  than  2  in.  on  all  sides, 


148       QUESTIONS  AND  ANSWERS  ON  THE 

except  from  the  surface  wired  over,  is  maintained;  con-; 
ductors  may  then  be  supported  on  porcelain  supports 
mounted  on  not  less  than  1/4  in.  fire  lining,  extending  at 
least  3  in.  beyond  conductors  at  either  side.  Supports  must 
raise  conductors  not  less  than  1/2  in.  from  surface  wired 
over,  and  be  not  over  12  in.  apart.  (4o-g-3.) 

Air  Pump  Motor  and  Circuits. 

833.  Can  knob  and  tube  work  be  used  instead  of  approved 
metal  conduit  or  approved  moulding? 

Yes,  provided  supports  raise  conductors  1/2  in.  from 
surface  wired  over  and  are  not  over  12  in.  apart.     (4O-h-i.) 

834.  Must  automatic  control  be  installed? 
Yes,  in  approved  metal  box.     (4o-h-2.) 

835.  When  air  pump  and  motor  are  enclosed,  is  a  wooden 
box  acceptable? 

Yes,  when  lined  with  metal  of  not  less  than  1/32  in. 
in  thickness.     (4O-h-2.) 

836.  May  boxes  surrounding  automatic  controls  in  air 
pump  and  motor  serve  as  outlet  boxes  in  which  taps,  joints, 
etc.,  may  be  freely  made? 

Yes,   when  conductors  are  run  in  metal  conduit. 
(40-h-2.) 
Main  Motor  Circuits  and  Devices. 

837.  Must  conductors  in  hood  be  protected  where  wires 
enter  car  to  prevent  moisture? 

Yes.     (40-1-1.) 

838.  Is  it  necessary  for  conductors  between  third-rail 
shoes  on  same  truck  to  be  supported  in  approved  non- 
metallic  fire-resisting  mouldings;  or  by  approved  iron  con- 
duit   (insulated   where   supported  by   approved  insulating 
cleats)? 

Yes.     (40-1-2.) 

839.  What  three  methods  only  are  permitted  for  con- 
ductors on  under  side  of  car,  and  may  connection  between 
controllers  and  contactors  be  run  otherwise  as  an  exception? 

First,  approved  metal  conduit  systems.     See  Questions 
811-812-813. 

Second,  approved  insulating,  fire -resisting,  moulding. 
Third,    approved    cleats    supporting    every    12    in. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   149 

Exception:  Conductors  with  flame -proof  braided 
outer  cover,  connecting  controllers,  or  controllers  and  con- 
tactors, may  be  run  as  a  cable,  provided  where  exposed  to 
weather  it  is  canvas  covered  by  tape  or  hose,  and  is  taped  or 
sewed  at  the  electrical  connections  and  ends. 

Conductors  without  flame -proof  outer  covering,  if 
surrounded  with  i/8-in.  flame -proof  cover,  may  be  used 
subject  to  same  provisions. 

All  of  above  kinds  of  installation  under  Exception 
may  be  run  full  length  of  car  for  main  motor  circuit  and 
devices.  (40-1 -4) 

840.  How  must  cables  be  run  above  floor  of  car? 
Specifically  provided  in  metal  conduit  or  wooden  box 

painted  with  two  coats  of  flame -proof  paint  inside;  box 
should  be  made  reasonably  water -proof  when  exposed  to 
water,  such  as  washing  of  car  floor.  (40 -i -4.) 

841.  Must  canvas  hose  or  tape  or  flame-proof  material 
surrounding  cables  be  painted  with  water-proof  insulating 
materials? 

Yes.     (40-1-4.) 

842.  Is  it  required  that  motors  be  so  drilled  on  double 
truck  cars  that  connecting  cables  can  leave  motor  on  side 
nearest  to  king  bolt? 

Yes.     (40-1-5.) 

843.  How  much  air  space  is  required  between  resistances 
proper  and  fire-resisting  material  of  car? 

Six  inches.     (40-1-6.) 

844.  What   three   methods  of  insulating  resistance  are 
specified? 

First,  supports  insulated  with  non -combustible  bush- 
ings or  washers. 

Second,  2  in.  of  insulating  material  between  the  re- 
sistances and  metal  work  of  the  car. 

Third,  mount  resistances  on  hardwood  bars  supported 
by  iron  stirrups  with  not  less  than  2  in.  insulation  surface 
between  foot  of  resistance  and  metal  stirrup ;  entire  surface 
of  bar  covered  with  at  least  1/8  in.  insulating  fire  lining. 
Conductor  insulation  about  6  in.  from  resistance  terminal 
should  be  replaced  if  needed  by  porcelain  bushing  or  asbestos 
sleeve.  (4O-i-6.) 

845.  How  must  controller  be  raised  above  platform  of  car? 


150       QUESTIONS  AND  ANSWERS  ON  THE 

By  a  not  less  than  i  in.  hardwood  block,  fitted  anc 
painted  to  prevent  moisture  working  between  it  and  the 
platform.  (40-1-7.) 

Lightning  Arresters. 

846.  How  is  it  recommended  that  lightning  arresters 
placed? 

Located  to  protect  auxiliary  service  in  addition 
main  motor  circuits.     (40-]-!.) 

847.  What  is  the  smallest  size  ground  conductor  accej 
No.  6  B.  &  S.     (4Q-J-2.) 

GENERAL  RULES 

848.  Are   approved,    tightly   fitting  insulating   bushin 
such  as  porcelain  or  glass,  required  where  conductors  pass  j 
through  floors? 

Yes.     (40-k-i.) 

849.  Is  it  necessary  that  such  bushings  used  in  passing 
through  floors  for  conductors  or  cables,  fit  closely  to  same? 

Yes.     (40-k-i.) 

850.  Is  moulding  forbidden  for  concealed  work? 

Code  recommends  in  any  car  wiring  work  it  shall 
not  be  concealed  except  where  readily  accessible.  (4O-k-2.) 

85 1.  Is  it  forbidden  to  tack  conductors  into  moulding? 
Code  recommends  they  shall  never  be  tacked  into 

moulding.     (4o-k-2.) 

852.  Is  it  mandatory  that  sharp  edges  in  conduit  or  in 
moulding  be  smoothed  to  prevent  injury  to  conductors?    j 

Yes.  Sharp  edges  in  conduit  must  be  avoided. 
(40-k-4.) 

Car  Houses. 

853.  Must  insulating  hanger  be  used  for  supporting  trol- 
ley wires? 

Yes.     (41 -a.) 

854.  How  far  apart  must  trolley  hangers  be  placed? 

So  that  in  case  of  a  break  trolley  wire  will  not  touch 
floor.  (4i-b.) 

855.  Is  an  emergency   cut-out  switch  or  two  or  more 
switches — one  for  the  trolley  and  one  for  other  currents — • 
required,  and  where  must  the  switch  or  switches  be  located? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    151 

Yes,  located  outside  of  building,  so  that  all  trolley 
wire  current  may  be  cut  at  one  point.  (41  -c.)  See  also  fine 
print  note.  (41-0.)  Read  858. 

856.  Is  it  necessary  for  the  trolley  wire  to  be  "dead" 
when  emergency  switch  is  open  at  all  points  within  100  ft. 
of  the  building? 

Yes.     (41 -c.) 

857.  Is  it  obligatory  to  cut  off  the  current  from  the  build- 
ing when  not  needed  in  the  building? 

Yes.     (41 -c.) 

858.  Must  lamps  and  stationary  motors  be  controlled  by 
separate  main  switch  independent  of  the  main  cut-out  switch 
described  under  Question  No.  855? 

Yes.     (41 -d.) 

Grounded  Trolley  Circuits. 

Following  questions  apply  where  current  for  lighting  and 
stationary  motors  is  from  an  earth  return  trolley  circuit. 

859.  May  light  and  power  be  taken  from  a  street  railway 
system  which  has  trolley  wires  with  a  ground  return  in  any 
buildings  except  electric  railroad  car  houses,  power  houses, 
passenger  and  freight  stations,  and  other  railways  company 
buildings? 

No.     (42-a.) 

860.  Are  cut-outs  and  switches  obligatory  to  cut-off  cur- 
rent from  motors  or  lights? 

Yes.     (41-6,  i  and  2.) 

86 1.  Where  must  controlling  cut-outs  and  switches  be 
cut  in? 

On  the  non -grounded  side.     (41-6-1  and  2.) 

862.  How  must  rails  be  bonded? 

At  each  joint  by  a  conductor  with  a  capacity  at  least 
equal  to  No.  o  B.  &  S.  gauge  annealed  copper  wire.  (41-6-3.) 

863.  How  must  rails  be  connected  to  outside  ground  re- 
turn circuit? 

By  a  not  less  than  No.  o  B.  &  S.  gauge,  copper  wire, 
or  equivalent  bonding  through  the  track.  (41-6-3.) 

864.  How  must  lighting  and  stationary  motor  circuits  be 
connected? 

Thoroughly  and  permanently  connected  to  rails  or 
to  wire  leading  to  outside  ground  return  circuit.  (41-6-3.) 


152  OFFICIAL  NATIONAL  ELECTRICAL  CODE 

865.  What  general    Code   rules  and  questions  apply  for 
installation  of  all  wiring  and  apparatus  in  Railway  Systems, 
except  as  provided  under  such  questions  as  787-827;  832-833; 
836;  838-839;  844? 

Rules  and  questions  for  constant  potential  systems. 
(4i-g.)    See  No.  249  and  321. 

866.  May  the  feeder  distributions  center  in  the  building? 
No.     (4i-h.) 

867.  Is  it  forbidden  to  leave  cars  in  electrical  connection 
with  the  trolley  wire  in  power  house? 

Yes.     (41 -i.) 

Flexible  Cord. 

868.  What  type  of  flexible  cord  must  be  used  throughout 
all  car-house  work? 

Type  P.  P.  W  p.  P.  A.  &  H.     (4i-f.) 


SECTION  EIGHT 

MARINE   WORK 

Allowable  Capacity  of  Wires. 

Generators. 

Wiring. 

Control  of  Freight  Departments. 

Cut-outs. 

Wattage  Limit. 

Wooden  Mouldings. 

Interior  Conduits. 

Protection  of  Wires. 

Portable  Conductors. 


SWITCHBOARDS 


Switches. 
Resistance  Boxes. 


FIXTURES 


Mounting. 

Wiring  of  Fixtures. 

Ceiling  Fixtures. 

Sockets. 

Signal  Lights. 

Bell  or  Other  Wires. 


MOTORS 
INSULATION  RESISTANCE 


153 


SECTION  EIGHT 


MARINE  WORK 

TABLE  OF  ALLOWABLE  CAPACITY  OF  WIRES 


B.  &  S.  G. 

Area  actual 
C.  M. 

No.  of 
strands 

Size  of 
strands. 
B.  &  S.  G. 

Amperes 

19 

1  288 

18 

1  624 

3 

17 
16 

2,048 
2  583 

6 

15 

3,257 

14 
12 

4,107 
6  530 

12 
17 

9^016 
11,368 

7 
7 

19 
18 

21 
25 

14  336 

7 

17 

30 

18,081 
22,799 

7 

7 

16 
15 

35 
40 



30,856 
38,912 
49,077 

19 
19 
19 

18 
17 
16 

50 
60 
70 

60,088 

37 

18 

85 

75,776 
99  064 

37 

61 

17 

18 

100 
120 



124,928 
157,563 
198  677 

61 
61 
61 

17 
16 
15 

145 
170 
200 

250  527 

61 

14 

235 

296^387 
373  737 

91 

91 

15 
14 

270 
320 

413  639 

127 

15 

340 

Generators.  (Code  rule  94.) 

Dry  places,  and  proof  covers  required  90. 

869.  Is  it  obligatory  that  frames  of  generators  be  insu- 
lated from  bed  plates? 

Yes.     (90 -b.) 
Wiring. 

870.  Is  exposed  work  allowed? 

No,  except  on  switchboards,  Approved  moulding, 
wood  or  metal,  and  conduit  required.  Exception :  Switch- 
boards and  for  portables.  Also  by  special  permission  in 
dynamo-rooms,  per  fine  print  note.  (91 -a.) 

871.  What  is  the  largest  solid  wire  allowed? 
No.  12  B.  &  S.     (9i-b.) 

872.  What  is  the  smallest  solid  wire  allowed? 

155 


156       QUESTIONS  AND  ANSWERS  ON  THE 

No.  14  B.  &  S.  Exception:  Fixture  wiring,  which 
may  be  No.  18.  (91 -b.) 

873.  How  must  splices  in  conductors  or  taps  be  made, 
and  when  are  they  permitted? 

When  necessary  splices  or  taps  are  permitted,  but 
must  be  avoided  as  far  as  possible;  must  be  made  mechan- 
ically and  electrically  certain  without  solder,  then  soldered; 
covered  with  insulating  compound  equivalent  wire  insula- 
tion; further  protected  by  water -proof  tape.  Whole  coated 
or  painted  with  water-proof  compound.  Exception  to  solder- 
ing joint  when  approved  soldering  device  is  used.  (91  -c.) 

874.  Give  requirements  and  test  for  wires  for  moulding 
work? 

"Must  have  an  approved  insulating  covering  at  least 
3/32  in.  in  thickness  and  be  covered  with  a  substantial 
waterproof  braid. 

The  physical  characteristics  shall  not  be  affected  by 
any  change  in  temperature  up  to  200°  F.  (93°  C.).  After 
two  weeks'  submersion  hi  salt  water  at  70°  F.  (21°  C.),  it 
must  show  an  insulation  resistance  of  100  megohms  per 
mile  after  three  minutes'  electrification  with  550  volts." 
(9i -d.) 

Control  of  Freight  Compartments. 

875.  Must    freight    departments    be   under   a   separate 
control? 

Yes.     (97-c.) 

Cut-outs. 

876.  Is  a  water-tight  and  fire-proof  cut-out  obligatory 
connecting  directly  to  the  mains  in  such  places  as  upper 
deck  holes,  cargo  spaces  and  fire  rooms,  and  under  what 
conditions? 

Water-tight  and  fire-proof  cut-outs  are  recommended, 
but  language  of  Code  is  not  mandatory  in  this  instance. 
They  are  optional  when  cut-outs  apply  to  circuits  requiring 
not  more  than  660  watts  energy.  (98 -b.) 

Note  No.  44:     Water-proof  cut-outs  should  be  used. 
Wattage  Limit. 

877.  What  is  the  wattage  limit  for  cut-outs,  except  for 
motors,  search  lights  and  diving  lamps? 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   157 

Six  hundred  and  sixty  watts  for  ultimate  dependence 
on  one  cut-out.  (gS-d.) 

Wooden  Mouldings. 

878.  What  are  the  requirements  for  the  construction  of 
wooden  moulding? 

Same  as  for  inside  wiring  in  ordinary  buildings. 
See  Section  6,  Division  One.  (ioi-6o-26-k  to  m.) 

879.  How   must   moulding   be   secured   when   run   over 
rivets,  beams,  etc.? 

Backing  strip  must  first  be  put  up  and  moulding 
secured  to  this.  (loi-a.) 

880.  Is  it  necessary  for  brass  screws  to  be  used  in  securing 
capping? 

Yes.     (loi-b.) 

Interior  Conduits. 

88 1.  What  are  the  requirements  for  wires  for  conduit 
work? 

Same  as  for  moulding  (No.  874.)  and  for  unlined 
metal  conduits,  conductors  must  conform  to  the  specifica- 
tions given  for  lined  conduits,  and  in  addition  have  a  second 
outer  fibrous  covering  at  least  1/32  hi.  in  thickness  and 
sufficiently  tenacious  to  withstand  the  abrasion  of  being 
hauled  through  the  metal  conduit."  (91  -g.)  (Type  R.  D.) 

882.  Can  wires  be  drawn  in  conduit  before  the  conduit 
system  mechanical  work  is  completed? 

No.     (gi-h.) 

883.  Must  approved  conduit  be  used  instead  of  moulding 
wherever  wires  are  exposed  to  severe  mechanical  injury; 
and  in  coal  bunkers,  boiler  rooms,  etc.? 

Yes.     (91 -i.) 

884.  Is  it  obligatory  that  on  alternating  systems  two  or 
more  wires  must  be  drawn  in  the  same  conduit? 

Yes.     (9i-j.) 

885.  What  are  the  general  requirements  for  interior  con- 
duits and  fittings  and  other  sundries? 

Same  as  for  interior  conduits  for  wiring  on  land. 
See  Section  6,  Division  2,  Code  Class  "C."  Rule  102,  Code 
Class  "F."  Questions  Nos.  321-333  inclusive  may  apply. 

886.  How  must  boxes  for  centers  of  distribution  and  not 


158       QUESTIONS  AND  ANSWERS  ON  THE 

affording  good  electrical  connection  with  the  rest  of  the 
system  be  treated? 

Bonded  by  means  of  suitable  bond  wires  properly 
attached,  and  with  exposed  ground  connections  properly 
made.  (iO2-f.)  See  questions  on  grounding  for  detail. 
Section  6,  Code  Class  "  C,"  373-378  inclusive. 

887.  How  many  circuits   of  the  same  system  may  one 
conduit  contain? 

Four  2 -wire  and  three  3 -wire.  Exception:  Special 
permission  from  insurance  department  having  jurisdiction. 
(9I-JO 

Protection  of  Wires. 

888.  How  must  wires  passing  through  water-tight  bulk- 
heads and  through  all  decks  be  protected? 

Metallic  stuffing  tube  lined  with  hard  rubber  must  be 
used.  (91 -e.) 

889.  In  the  case  of  deck  tubes,  what  extra  protection 
must  be  given  to  prevent  mechanical  injury  to  the  metallic 
stuffing  tube? 

Must  be  boxed  near  the  deck.     (91-6.) 

890.  Where  wires  pass  through  beams  and  non-water- 
tight bulkheads,  how  thick  must  the  required  bushing  of 
hard  rubber  tubing  be  made? 

One-eighth  inch  thick.     (91 -f.) 

Portable  Conductors. 

891.  How  many  stranded  wires  are  allowed  in  portable 
conductors? 

Two.     (92-a.) 

892.  What  is  the  smallest  gauge  conductor  permitted? 
Fourteen  B.  &  S.     (92-a.) 

893.  What  kind  of  a  covering  must  a  stranded  conductor 
in  a  portable  cable  have? 

Slow -burning,  tough  braided  outer  covering.     (92-3.) 

894.  Give  description  of  portable  conductors  extra  re- 
quirement in  thickness  of  insulation  and  general  make-up 
over  ordinary  portables? 

When  exposed  to  moisture  and  mechanical  injury 
(as  for  use  on  decks,  hold  and  fire  rooms)  each  conductor 
to  have  solid  insulation  at  least  1/32  in.,  protected  by  tough 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    159 

braid.  Two  conductors  shall  then  be  stranded  together, 
using  a  jute  filling.  Whole  shall  be  covered  with  a  layer  of 
flax,  either  woven  or  braided,  at  least  1/32  in.  in  thickness, 
and  treated  with  a  non-inflammable  water -proof  compound. 
(92 -a.)  See  Table  No.  18,  Section  9. 

895.  When  a  greater  conductivity  than  No.  12  B.  &  S. 
gauge  is  used,  what  must  be  the  sizes  of  the  wires  making 
up  the  strands;  how  shall  it  be  made? 

Stranded  in  series  of  7,  19,  37,  61,  91,  or  127  wires, 
as  may  be  required.  Strand  consisting  of  one  central  wire ; 
remainder  laid  around  it  concentrically,  each  layer  to  be 
twisted  in  opposite  direction  from  preceding.  (94.) 

SWITCHBOARDS 

896.  Can  wood  be  used  for  main  switchboards? 
No.     (95 -a.) 

897.  What  special  kinds  of  insulation  and  protective  cov- 
ering is  required  for  conductors  at  switchboard? 

Flame -proof  braided  and  otherwise  as  required  for 
moulding  or  conduit  work.  (95  -e.) 

Switches. 

898.  What  special  requirements  apply  for  marine  switch- 
boards not  mandatory  in  other  classes  of  work? 

Must  have  main  cut-out  and  ammeter  for  each  gen- 
erator, as  well  as  main  switch.  Second,  volt  meter  and 
ground  detector.  Third,  cut-out  and  switch  for  each  side 
of  circuit  leading  from  board.  (95  -c  and  d.) 

Note:  Switchboard  must  be  made  of  slate  or  marble  or 
similar  material,  free  from  moisture,  and  accessible  from  all 
sides.  (95-a-b.)  Section  6,  Division  Three  questions  ap- 
plicable. 

899.  What  kind  of  special  switch  is  required  for  marine 
switchboard? 

Knife  bladed.     (97-0.) 

900.  How  must  switches  on  deck  and  otherwise  exposed 
to  dampness  be  treated? 

Enclosed  in  water-tight  case.     (97-3.) 

Resistance  Boxes. 

901.  How  must  resistance  boxes  not  located  on  switch- 
board be  mounted? 


™ 


160       QUESTIONS  AND  ANSWERS  ON  THE 

Away  from  combustible  material.  (Q6-a.)  Code 
Rule  78  applying.  See  also  Questions  Nos.  390-410.  in- 
clusive. For  Auto  starters  read  411  to  418  inclusive.  All 
4-c  (reference)  questions  apply. 

FIXTURES 

Mounting. 

902.  Give  special  requirements  for  mounting  fixtures? 
Blocks  made  from  well  seasoned  lumber,  treated  with 

two  coats. white  paint  or  shellac.     (99-a.) 

903.  Are  vapor-proof  globes  obligatory  where  lamps 
exposed  to  dampness? 

Yes.     (99-b.) 

904.  What  special  requirement  is  made  for  lamps  where 
exposed  to  mechanical  injury? 

Must  be  surrounded  by  a  globe  which  in  turn  is  pro- 
tected by  stout  wire  guard.  (99-c.) 

Wiring  of  Fixtures. 

905.  What  special  grade  of  insulation  is  required  fo 
marine  work? 

Same  as  portable  conductors  not  exposed  to  moistur 
or  injury.     (99-d.)     Type  letter  P.  O.  applies. 

Ceiling  Fixtures. 

906.  What  special  mechanical  provision  is  required  upoi 
all  ceiling  fixtures  over  2  ft.  in  length? 

Must  be  provided  with  stay  chains.     (99-6.) 

Sockets. 

907.  What  special  kind  of  sockets  are  required  for  marin 
work? 

Requirements  the  same  as  for  other  classes  of  worl 
under  same  conditions.  Read  709  to  732. 

Signal  Lights. 

908.  Is  it  obligatory  for  signal  lights  to  be  provided  with 
an  approved  tell-tale  board,   located  preferably  in  pilot 
house,  which  will  immediately  indicate  a  burned-out  lamp? 

Yes.     (103 -a.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   161 

Bell  or  Other  Wires. 

909.  Can  bell  or  other  wires  be  run  in  the  same  duct  as 
electric  lighting  or  power  wires? 

No.     (93 -a.) 

MOTORS 

910.  What  are  the  general  requirements  for  motors,  al- 
ternating and  direct? 

Must  comply  with  requirements  as  indicated  under 
questions,  Section  i,  Motors,  and  Code  Class  "A." 

Must  also  be  thoroughly  insulated.  On  hoists  and 
winches,  must  be  insulated  from  bed  plates  by  hard  rubber 
fiber  or  other  similar  insulating  material.  (104 -a  and  b.) 

General  requirements  demanding  name  plate,  water- 
proof cover,  and  other  details  same  as  in  Section  One. 

INSULATION  RESISTANCE 

"The  wiring  in  any  vessel  must  test  free  from  grounds; 
i.e.,  the  complete  installation  must  have  an  insulation  be- 
tween conductors  and  between  all  conductors  and  the 
ground  (not  including  attachments,  sockets,  receptacles, 
etc.)  of  not  less  than  the  following: 

Up  to       25  amperes 800,000  ohms. 

Up  to        50  amperes 400,000  ohms. 

Up  to      100  amperes 200,000  ohms. 

Up  to     200  amperes 100,000  ohms. 

Up  to     400  amperes 50,000  ohms. 

Up  to     800  amperes 25,000  ohms. 

Up  to  1,600  amperes 12,500  ohms. 

"All  cut-outs  and  safety  devices  in  place  in  the  above. 
"Where  lamp  sockets,  receptacles  and  electroliers,  etc., 
are  connected,  one-half  of  the  above  will  be  required."    (105.) 


11 


SECTION  NINE 

In  this  section  will  be  found  general  information  upon 
approved  wire  markings  and  the  requirements  for  wire  and 
material  as  demanded  by  the  Code.  The  1911  requirements 
have  raised  the  standard  of  rubber  insulation  for  wire 
materially,  requiring  20  per  cent,  of  rubber  in  the  compound. 

For  mechanical  and  chemical  tests  of  the  compound  the 
Underwriters  Laboratories,  131  East  Ohio  street,  Chicago, 
111,  have  provided  special  specifications.  Read  also  50-g-h- 
and  i  of  the  Code. 

The  Underwriters'  Laboratories  now  has  approved  coils 
tagged  at  factories  before  shipment. 

Many  of  the  tables  from  the  1911  Code  are  assembled 
here  for  convenient  reference. 

The  wire-conduit  table  has  been  added  as  a  matter  of 
general  interest. 


163 


CONTENTS 


pproved  Wire  Markings. 
Type  Letters  of  Wire. 
Varnished  Cambric  Cabl 
Table  No.    1.  Allowable  capacity  of  wire. 
Table  No.    2.  Slow-burning    weather-proof    wire   require- 
ments. 

3.  Slow-burning  wire  requirements. 

4.  Weather-proof  wire  requirements. 

5.  Insulation  tests  for  0-600  volts  R.  C.  wire. 


Table  No. 
Table  No. 
Table  No. 
Table  No. 


6.  Insulation  tests  for  601-3500   volts   R.    C. 


wire. 


Table  No.    7.  Insulation  tests  for  3500-7000  volts   R.  C. 
wire. 

Table  No.    8.  Requirements  for  conduit  wires.     Type  let- 
ters R.  D. 

Table  No.    9.  Requirements  for  fixture  wires.     Type  letters 
F.  32-F.  64. 

Table  No.  10.  Requirements  for  flexible  cord.     Type  let- 
ter C. 

Table  No.  11.  Requirements  for  flexible   cord.      Type  let- 
ter P. 

Table  No.  12.  Requirements  for  flexible  cord.     Type  letter 
P.  Wp. 

Table  No.  13.  Requirements  for  flexible  cord.     Type  letter 
P.  O. 

Table  No.  14.  Requirements  for  flexible  cord  for  portable 
heating  devices.     Type  letter  H. 

Table  No.  15.  Requirements   for   armored    portable    cord. 
Type  letter  P.  A. 

Table  No.  16.  Requirements  for  theater  cables. 

Table  No.  17.  Requirements  for  elevator  cables. 

Table  No.  18.  Requirements   for   portable   conductors   for 
marine  work. 

Table  No.  19.  Dimensions  of  approved  tubes. 

Table  No.  20.  Sizes  of  approved  knobs. 

Table  No.  21.  Spacings  of  approved  cleats. 

Table  No.  22.  Sizes  and  weights  of  unlined  conduits. 

Table  No.  23.  Spacings  for  cut-outs. 

Table  No.  24.  Rating  of  plug,  cartridge,  scalable  service  and 
meter  cut-outs. 
165 


166        QUESTIONS  AND  ANSWERS  ON  THE 

Table  No.  25.  Dimensions  of  National  Electrical  Code 

ridge  enclosed  fuses. 

Table  No.  26.  Spacings  for  enclosed  fuse  terminals. 
Table  No.  27.  Spacings  for  knife  switches. 
Table  No.  28.  Spacings  for  switch  and  cut-out  terminals. 
Table  No.  29.    Switch  and  bus  spacings  for  tablets  and 

panel  boards. 

Table  No.  30.  Breaking  capacity  of  circuit-breakers. 
Table  No.  31.  Wiring  in  buildings  insulation  resistance  test. 
Table  No.  32.  Number  of  wires  in  rigid  conduit. 

WIRE  MARKINGS  AND  TYPE  LETTER. 

When  received  from  factory  approved  wire  must  have 
distinctive  marking  entire  length  of  coil;  also  be  tagged  or 
marked. 

"  1.  The  maximum  voltage  at  which  the  wire  is  designed 

to  be  used. 

"2.  The  words  '  National  Electrical  Code  Standard.' 
"  3.  Name  of  the  manufacturing  company  and,  if  desired, 

trade  name  of  the  wire. 
"  4.  Month  and  year  when  manufactured. 
"  5.  The  proper  type  letter  for  the  particular  style  of  wire 
or  cable  as  given  for  each  type  of  insulation  in  Code 

rules  50  to  57  inclusive. 

"Wires   described  under  Table  No.  4  need  not  have 
distinctive  marking,  but  are  to  be  tagged. 

VARNISHED  CAMBRIC  CABLE. 


The  April,  1912,  List  of  Fittings  says: 

"Varnished  cambric  cable  insulation  consisting  of 
cambric  with  protecting  covering  of  braid  or  a  lead  sheath. 

Present  installation  rules  do  not  recognize  a  material  9f  this 
character.  Laboratory  tests  show  favorable  results  and  limited 
field  experience  to  date  is  satisfactory.  It  is,  therefore,  recom- 
mended that  local  inspection  departments  having  iurisdiction 
allow  the  use  of  the  cable  as  the  equivalent  to  a  rubber  covered 
conductor  in  such  quantities  and  location  as  will,  in  their  judg- 
ment, afford  information  sufficient  to  warrant  consideration  of 
change  in  present  rules." 

The  Underwriters'  Laboratories  type  letter  marking  is  as 
follows: 

For  use  on  Type  letter 

0-600  volts  R.  S. 

0-1500  R.  S.  15 

0-2500  R.  S.  25 

0-3500  R.  S.  35 


OFFICIAL  NATIONAL  ELECTRICAL  CODE  167 

For  use  on  Type  letter 

0-5000  R.  S.  50 

0-7000  R.  S.  70 

Slow-burning  weather-proof      .  S.  B.  W. 

Slow-burning  S.  B. 

Weather-proof  W.  R. 

Conduit  wire  R.  D. 

Armored  cable  A.  C. 

Lead-covered  cable  R.  S.  L. 

Fixture  wires  {  ^ 

Flexible  cords 

For  pendant  lamps,  free  in  air  C. 

For  pendants  in  damp  places  C.  Wp. 

For  portables  P. 

For  portables  in  damp  places  P.  Wp. 

For  portables  in  dwellings,  etc.  P.  O. 

Armored  portable  P.  A. 

Portable  cord  for  heating  apparatus  H. 

Theater  stage  cable  T. 

Theater  border  cable  B. 

Elevator  lighting  and  control  cable  E. 

Marine  portable  No  type  letter. 

TABLE   NO.    i 

Table  B  of  Table  No.  1  may  be  used  for  large  starting  cur- 
rent alternating  type  motors,  where  rubber  insulation  is 
used,  unless  a  time  element  circuit-breaker  is  installed  as 
the  only  protector. 

Example:  A  No.  5  B.  &  S.  wire,  Table  A  (rubber-cov- 
ered), is  allowed  54  amperes  for  all  ordinary  work  such  as 
direct-current  motors.  When  the  same  wire  is  used  for 
alternating  current  motors  of  large  starting  current  the  same 
wire  (rubber-covered)  is  allowed  77  amperes  under  Table  B. 

The  selection  of  the  proper  size  of  wire  for  large  alter- 
nating current  motors  is  at  the  present  time  a  matter  of 
individual  treatment  of  each  case,  according  to  its  start- 
ing load,  and  using  Table  B  and  rubber-covered  wire. 

Where  circuit-breakers  are  used  on  alternating-current 
work  for  motor  protection  they  must  be  set  not  over  30  per 
cent,  above  allowable  carrying  capacity  of  the  wire  unless 
fuses  protecting  circuit  are  also  used. 


168       QUESTIONS  AND  ANSWERS  ON  THE 


TABLE   No.  1 
ALLOWABLE  CAPACITY  OF  WIRES 


Table 

A 

Table 

B 

B.  &  S.  G. 

Rubber 
insulation 
Amperes 

Other 
insulations 
Amperes 

Circular  mils 

18 

3 

5 

1,624 

16 

6 

8 

2,583 

14 

12 

16 

4,107 

12 

17 

23 

6,530 

10 

24 

32 

10,380 

8 

33 

46 

16,510 

6 

46 

65 

26,250 

5 

54 

77 

33,100 

4 

65 

92 

41,740 

3 

76 

110 

52,630 

2 

90 

131 

66,370 

1 

107 

156 

83,690 

0 

127 

185 

105,500 

00 

150 

220 

133,100 

000 

177 

262 

167,800 

0000 

210 

312 

211,600 

Circular  mils 

200,000 

200 

300 

300,000 

270 

400 

40o]oOO 

330 

500 



500,000 

390 

590 

600,000 

450 

680 

700^000 

500 

760 

800,000 

550 

840 

900,000 

600 

920 

1,000,000 

650 

1,000 

1,100,000 

690 

1,080 

1,200,000 

730 

1,150 



1,300,000 

770 

1,220 

1,400,000 

810 

1,290 

1,500,000 

850 

1,360 

1  ,600,000 

890 

1,430 

1  700  000 

930 

1,490 

1  800  000 

970 

1,550 

1  900  000 

1,010 

1,610 

2,000,000 

1,050 

1,670 

"Aluminum  wire  is  rated  84  per  cent,  of  copper,  same 
insulations." 

The  lower  limit  is  specified  for  rubber-covered  wires  to  prevent  gradua 
deterioration  of  the  high  insulations  by  the  heat  of  the  wires,  but  not 
from  fear  of  igniting  the  insulation.  The  question  of  drop  is  not  taken 
into  consideration  in  the  above  tables.  fi8-a.) 

Copper  conductors  must  be  tinned.      (50-a.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   169 

TABLE   No.  2 
SLOW-BURNING  WEATHER-PROOF  WIRE 

Type  Letters  S.  B.  W. 

This  wire  is  not  as  burnable  as  "  weather-proof "  nor  as  subject  to 
ftening  under  heat.     It  is  not  suitable  for  outside  work. 

a.  The  insulation  must  consist  of  two  coatings,  one  to  be 
-proof  in  character  and  the  other  to  be  weather-proof, 
fire-proof  coating  must  be  on  the  outside  and  must 
comprise  about  six-tenths  of  the  total  thickness  of  the  wall. 
The  completed  covering  must  be  of  a  thickness  not  less  than 
that  given  in  the  following  table: 

B.  &  S.  gage  Thickness 

14  to        8 3/64  in. 

7  to        2 1/16  in. 

1  to  0000 5/64  in. 

Circular  mils 

250,000  to     500,000 3/32  in. 

500,000  to  1,000,000 7/64  in. 

Over  1,000,000 1/8    in. 

Measurements  of  insulating  wall  are  to  be  made  at  the  thinnest  portion. 

6.  The  fire-proof  coating  shall  be  of  the  same  kind  as 
that  required  for  "slow-burning  wire,"  and  must  be  finished 
rith  a  hard,  smooth  surface. 

c.  The  weather-proof  coating  shall  consist  of  a  stout 
braid,  applied  and  treated  as  required  for  "weather-proof 
wire."  (5i-a-b-c.) 


170       QUESTIONS  AND  ANSWERS  ON  THE 

TABLE   No.  3 

SLOW-BURNING  WIRE 

Type  Letters  S.  B. 

a.  The  insulation  must  consist  of  three  braids  of  cotton 
or  other  thread,  all  the  interstices  of  which  must  be  filled 
with  the  fire-proofing  compound  or  with  material  hav- 
ing equivalent  resisting  and  insulating  properties.  The 
outer  braid  must  be  specially  designed  to  withstand  abrasion, 
and  its  surface  must  be  finished  smooth  and  hard.  The 
completed  covering  must  be  of  a  thickness  not  less  than 
that  given  in  the  Table  2. 

The  solid  constituent  of  the  fire-proofing  compound  must  not  be  sus- 
ceptible to  moisture,  and  must  not  burn  even  when  ground  in  an  oxi- 
dizable  oil,  making  a  compound  which,  while  proof  against  fire  and 
moisture,  at  the  same  time  has  considerable  elasticity,  and  which  when 
dry  will  suffer  no  change  at  a  temperature  of  250°  F.  (121°  C.)t  and 
which  will  not  burn  at  even  a  higher  temperature. 

This  is  practically  the  old  so-called  "underwriters"  insulation.  It  ia 
especially  useful  in  hot,  dry  places  where  ordinary  insulations  would 
perish,  and  where  wires  are  bunched,  as  on  the  back  of  a  large  switch- 
board or  in  a  wire  tower,  so  that  the  accumulation  of  rubber  insulation 
would  result  in  an  objectionably  large  mass  of  highly  inflammable 
material.  (52-a.) 


TABLE   No.  4 

WEATHER-PROOF  WIRE 

Type  Letters  W.  R. 

a.  The  insulating  covering  shall  consist  of  at  least  three 
braids,  all  of  which  must  be  thoroughly  saturated  with  a 
dense  moisture-proof  compound,  applied  in  such  a  manner 
as  to  drive  any  atmospheric  moisture  from  the  cotton  braid- 
ing, thereby  securing  a  covering  to  a  great  degree  water- 
proof and  of  high  insulating  power.  This  compound  must 
not  drip  at  160°  F.  (71°  C.).  The  thickness  of  insulation 
must  not  be  less  than  that  given  in  the  Table  2,  and  the 
outer  surface  must  be  thoroughly  slicked  down. 

This  wire  is  for  use  outdoors,  where  moisture  is  certain  and  where 
fire- proof  qualities  are  not  necessary.  (S3-a.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    171 


TABLE  No.  5 

TESTS  ON  COMPLETED  LENGTHS  0-600  VOLT  CLASS 
Type  Letters  R.  S. 


Size 

Thickness  in 
64ths  inches 

Megohms  per  mile 
after  12  hrs. 
immersion 

Voltage 
test  1 
minute 

14 

3/64 

300 

1,500 

12 

3/64 

250 

1,500 

10 

3/64 

225 

1,500 

8 

3/64 

200 

1,500 

6 

1/16 

200 

2,000 

4 

1/16 

150 

2,000 

2 

1/16 

125 

2,000 

1 

5/64 

150 

2,500 

0 

5/64 

125 

2,500 

00 

5/64 

125 

2,500 

000 

5/64 

100 

2,500 

0000 

5/64 

100 

2,500 

225,000  C.  M. 

3/32 

100 

3,000 

300,000  C.  M. 

3/32 

100 

3,000 

400,000  C.  M. 

3/32 

100 

3,000 

500,000  C.  M. 

3/32 

100 

3,000 

600,000  C.  M. 

7/64 

100 

3,500 

700,000  C.  M. 

7/64 

100 

3,500 

800,000  C.  M. 

7/64 

100 

3,500 

900,000  C.  M. 

7/64 

100 

3,500 

1,000,000  C.  M. 

7/64 

100 

3,500 

1,250,000  C.  M. 

1/8 

100 

3,500 

1,500,000  C.  M. 

1/8 

75 

3,500 

1,750,000  C.  M. 

1/8 

60 

3,500 

2,000,000  C.  M. 

1/8 

50 

3,500 

172       QUESTIONS  AND  ANSWERS  ON  THE 


TABLE   No.  6 

MAXIMUM  OPERATING  VOLTAGE 
1500  V.  Type  Letters  R.  S.— 15 


Size 

Thickness 
insulation. 

Insulation 
resistance 
niegoh  ms 
one  minute 
60°    F 

Volts  test 
for  one 
minute 

B   &  S.  Gauge 
14-8 

1/16 

600 

4  000 

7-2 

5/64 

300 

4  000 

1-0000 

3/32 

200 

4  000 

C.  M. 

225,000-500,000 

7/64 

175 

4  000 

525,000-1  ,000,000 

1/8 

150 

4  000 

Over  1,000,000  

9/64 

100 

4  000 

MAXIMUM  OPERATING  VOLTAGE 
2500  V.  Type  Letters  R.  S. — 25 


(5o-f  and  e.) 


Size 

Thick 
ins. 

Ins.  res. 
meg. 

Volts 
test 

B.  &  S.  Gauge 
14-8 

3/32 

700 

6  250 

7-2 

3/32 

350 

6  250 

1-0000  

7/64 

250 

6  250 

C.  M. 

225,000-500,000  

1/8 

200 

6,250 

525,000-1,000,000  
Over  1,000,000  

9/64 
10/64 

175 
125 

6,250 
6,250 

MAXIMUM  OPERATING  VOLTAGE 
3500  V.  Type  Letters  R.  S.— 35 


(5o-f  and  e.) 


Size 

Thick 
ins. 

Ins.  res. 
meg. 

Volts 
tests 

B.  &  S.  Gauge 
14-8 

4/32 

850 

8  750 

7-2 

4/32 

450 

8750 

1-0000 

4/32 

300 

8,750 

C.  M. 

225,000-500,000  

9/64 

225 

8,750 

525,000-1,000,000  

10/64 

200 

8,750 

Over  1  000  000 

11/64 

150 

8,750 

(50-1  and  e.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE   173 

TABLE   No.  7 

MAXIMUM  OPERATING  VOLTAGE 
5000  V.  Type  Letters  R.  S.— 50 


Size 

Thick 
ins. 

Ins. 
res. 
meg. 

Volts 
test 

B.  &  S.  Gauge 
14-8 

6/32 

1  000 

12  500 

7-2 

6/32 

650 

12  500 

1-0000  
C.  M. 
225,000-500,000  
525,000-1,000,000  
Over  1,000,000 

6/32 

6/32 
6/32 

7/32 

450 

300 
225 
175 

12,500 

12,500 
12,500 
12  500 

(5o-f  and  e.) 


MAXIMUM  OPERATING  VOLTAGE 
7000  V.  Type  Letters  R.  S.— 70 


Tns 

Size 

Thick 

reg. 

Volts 

ms. 

test 

meg. 

B.  &  S.  Gauge 

14-8  

8/32 

1,200 

17,500 

7-2 

8/32* 

800 

17  500 

1-0000 

8/32 

550 

17  500 

C.  M. 

225,000-500,000     . 

8/32 

400 

17  500 

525,000-1,000,000  

8/32 

275 

17  500 

Over  1,000,000  

9/32 

200 

17  500 

(5o-f  and  e.) 


174       QUESTIONS  AND  ANSWERS  ON  THE 


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OFFICIAL  NATIONAL  ELECTRICAL  CODE     177 


FLEXIBLE  CORDS 

(Limited  to  300  Volts,  Street  Railways  Excepted) 

The  Code,  Class  D,  includes  under  flexible  cord  the 
following: 

Cords  for  pendant  lamps  and  for  portable  use  including 
elevator,  lighting  and  control  cables,  and  theater,  stage  and 
border  cables.  The  principal  differences  lie  in  the  thick- 
nesses of  insulation,  and  the  number  of  protective  outer 
coverings,  although  in  theater  stage  cable  the  maximum 
conductor  capacity  for  each  of  three  conductors  is  limited  to 
No.  4  B.  &  S. 

Following  tables  are  compiled  from  the  specified  require- 
ments: 

The  only  other  "approved  method"  that  is  accepted 
instead  of  the  "first  protection"  of  fine  cotton  over  strands 
is  where  the  method  employed  in  large  cables  of 

1.  Tinning  each  strand  separately. 

2.  Surrounding  a  center  with  six  strands  laid  spirally. 

3.  Surrounding  this  by  other  layers  similarly  laid,   is 
used. 


12 


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TABLE  No.  15 
ARMORED  PORTABLE 
TYPE  LETTERS  P.  A. 

[Minimum  requirements] 

Insulation 

Homogeneous  ru 
compound 
dry  places  1/32  in 
damp  places  3/64 

Same  as  above  a; 
dry  places  3/64  in 
damp  places  3/64 

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OFFICIAL  NATIONAL  ELECTRICAL  CODE     187 


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I II II 


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5  £  -S  ^  2  '2 

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188        QUESTIONS  AND  ANSWERS  ON  THE 


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OFFICIAL  NATIONAL  ELECTRICAL  CODE     189 


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190       QUESTIONS  AND  ANSWERS  ON  THE 
TABLE  No.  19 

Tubes. — Dimensions  of  walls  and  heads  must  be  at  least 
as  great  as  those  given  in  the  following  table: 


Diameter 
of  hole 

External 
diameter 

Thickness 
of  wall 

External 
diameter 
of  head 

Length 
of  head 

5/16  in. 

9/16  in. 

1/8  in. 

13/16  in. 

1/2  in. 

3/8  in. 

11/16  in. 

5/32  in. 

15/16  in 

1/2  in. 

1/2  in. 

13/16  in. 

5/32  in. 

1  3/16  in. 

1/2  in. 

5/8  in. 

15/16  in. 

5/32  in. 

1  5/16  in. 

1/2  in. 

3/4  in. 

1  3/16  in. 

7/32  in. 

1  11/16  in. 

5/8  in. 

lin. 

1  7/16  in. 

7/32  in. 

1  15/16  in. 

5/8  in. 

1  1/4  in. 

1  13/16  in. 

9/32  in. 

2  5/16  in. 

5/8  in. 

1  1/2  in. 

2  3/16  in. 

11/32  in. 

2  11/16  in. 

3/4  in. 

1  3/4  in. 

2  9/16  in. 

13/32  in. 

3  1/16  in. 

3/4  in. 

2  in. 

2  15/16  in. 

15/32  in. 

3  7/16  in. 

3/4  in. 

2  1/4  in. 

3  5/16  in. 

17/32  in. 

3  13/16  in. 

1  in. 

2  1/2  in. 

3  11/16  in. 

19/32  in. 

4  3/16  in. 

1  in. 

An  allowance  of  1/64  in.  for  variation  in  manufacturing  will  be  per- 
mitted, except  in  the  thickness  of  the  wall.    (6i-d.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    191 
TABLE  No.  20 

Knobs. — Must  be  so  constructed  as  to  separate  the  wire 
at  least  1  in.  from  the  surface  wired  over,  and  also  conform 
to  the  following  minimum  dimensions: 


Size  of  base,  inches 

Solid  knobs, 

Split 

fe^ifeMf  4t(»  Ip 

Size  of  wire 

groove, 
inches 

knobs, 
thickness 
of  cap, 

Square  knobs 

inclusive 

Circular 
knobs, 

or  single 
wire  cleats 

inches 
from  top 

diameter 

Depth 

Diam- 
eter 

of  wire 
groove 

Width 

Length 

14-10 

1  1/8 

3/4 

1  3/4 

3/16 

1/4 

3/8 

8-4 

1  1/2 

7/8 

2 

5/16 

5/16 

5/8 

2-00 

2 

1 

21/4 

7/16 

5/8 

5/8 

)00-300,000 
C.  M. 

21/2 

1  1/8 

23/4 

7/16 

25/32 

7/8 

400,000- 

1,000,000 

3 

1  3/8 

33/4 

5/8 

1  1/4 

1 

C.  M. 

(64-e.) 


192       QUESTIONS  AND  ANSWERS  ON  THE 
TABLE  No.  21 

Cleats. — Must    conform    to    the    spacings    given    in    the 
following  table: 


Voltage 
0-300 


Distance  from  wire 

to  surface 

1/2  in. 


Distance  between 

wires 
2  1/2  in. 


This  rule  will  not  be  interpreted  to  forbid  the  placing  of  the  neutral  of 
a  three-wire  system  in  the  center  of  a  three- wire  cleat  where  the  difference 
of  potential  between  the  outside  wires  is  not  over  300  volts,  provided  the 
outside  wires  are  separated  21/2  in.  (62  -e.) 


TABLE  No.  22 

WEIGHTS  AND  DIMENSIONS  OF  UNLINED,  RIGID  METAL 
CONDUIT. 

Finished   conduit   to   have   weight   per   100  ft.   not  less 
than  that  given  in  the  following  table: 


Trade 
size,  inches 

Approx.  internal 
diameter,  inches 

Min.  thickness 
of  wall,  inches 

Wt.  per  100  ft.  Ib. 

1/2 

.62 

.100 

75 

3/4 

.82 

.105 

104 

1 

1.04 

.125 

152 

1  1/4 

1.38 

.135 

209 

1  1/2 

1.61 

.140 

250 

2 

2.06 

.150 

350 

2  1/2 

2.46 

.200 

535 

3 

3.06 

.210 

710 

(58-j.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE     193 

TABLE   No.  23 
SPACINGS  FOR  OPEN  LINK  CUT-OUTS 

Only  Slate  and  Marble  Base  Approved 


Minimum  separation  of 
nearest  metal  parts  of 
opposite  polarity 

Minimum 
break- 
distance 

Not  over  125  volts 
10  amperes  or  less  
11—100  amperes 

3/4  in. 
1  in 

3/4  in. 
3/4  in 

101-300  amperes.    . 

1  in 

1  in 

301-1,000  amperes  

Not  over  250  volts 
10  amperes  or  less  
11—100  amperes  

11/4  in. 

11/2  in. 
1  3/4  in. 

1  1/4  in. 

1  1/4  in. 
1  1/4  in. 

101-300  amperes 

2  in 

1  1/2  in 

301-1  000  amperes 

2  1/2  in 

2  in 

(67-J-) 


TABLE   No.  24 

STANDARD  PLUG  OR  CARTRIDGE  CUT-OUTS 

Not  over  250  Volts  Not  over  600  Volts 

0-30    amperes.  0-30    amperes. 

31-60    amperes.  31-60    amperes. 

61-100  amperes.  61-100  amperes. 

101-200  amperes.  101-200  amperes. 

201-400  amperes.  201-400  amperes. 
401-600  amperes. 

Scalable  Service  and  Meter  Cut-outs 

Not  over  250  Volts  Not  over  600  Volts 

0-31    amperes  0-30    amperes 

31-60    amperes  31-60    amperes 

61-100  amperes  61-100  amperes 

101-200  amperes  101-200  amperes 

(67-0.) 
13 


194       QUESTIONS  AND  ANSWERS  ON  THE 


TABLE 

DIMENSIONS  OF  THE  NAT 
STANDARD  CARTRID 


FORM  1.  CAETRIDGE  FUSE — FERRULE  CONTACT 


Voltage 

A 

B 

C 

Rated 
capacity 

Amperes 

Length  over 
terminals. 

Inches 

Distance 
between 
contact  clips. 

Inches 

Width  of 
contact 
clips. 

Inches 

Not  over  250.  .  . 

0-30 
31-60 

I' 

1 

1  3/4 

1/2 
5/8 

61-100 
101-200 
201-400 
401-600 

M      57/3 

5     7  1/8 
8      85/8 
fe    103/8 

4 
4  1/2 
5 
6 

7/8 
1  1/4 
1  3/4 
2  1/8 

Not  over  600.  .  . 

0-30 
31-60 

1      5 

£      5  1/2 

4 

4  1/4 

1/2 
5/8 

7/8 
1  1/4 
1  3/4 

61-100 
101-200 
201-400 

<N         7  7/g 

g      9  5/8 
£    11  5/8 

6 

7 
8 

OFFICIAL  NATIONAL  ELECTRICAL  CODE     195 


NO.  25 

IONAL  ELECTRICAL  CODE 

GE  ENCLOSED  FUSE 


FORM  2.     CARTRIDGE  FUSE — KNIFE  BLADE  CONTACT 


D 

E 

F 

G 

Diameter  of 

Minimum  length 

Diameter 

Width  of 

Rated 

ferrules  or 

of  ferrules  or  of 

of  tube. 

terminal 

capacity 

thickness  of 

terminal  blades 

blades. 

amperes 

terminal  blades. 

outside  of  tube. 

Inches 

Inches 

Inches 

Inches 

9/16 

1/2 

1/2 

- 

0-30 

13/16 

5/8 

3/4 

£* 

31-60 

£ 

1/8 

1 

1 

3/4    „ 

61-100 

3/16 

1  3/8 

1  1/2 

1  1/8     a 

101-200 

1/4 

17/8 

2 

1  5/8     g 

201-400 

1/4 

2  1/4 

2  1/2 

2            * 

401-600 

13/16 

1/2 

3/4 

S 

0-30 

1  1/16 

5/8 

1 

£ 

31-60 

1/8 

1 

1  1/4 

3/4  N 

61-100 

3/16 

1  3/8 

1  3/4 

1  1/8  g 

101-200 

1/4 

1  7/8 

2  1/2 

1  5/8  £ 

201-400 

(68-g.) 


196       QUESTIONS  AND  ANSWERS  ON  THE 


TABLE   No.  26 

SPACINGS  FOR  ENCLOSED  FUSE  TERMINALS 
Not  over  250  Volts: 

A.  Cartridge  fuse  (ferrule  contact). 

B.  Approved  plugs  for  Edison  cut  outs  not  exceed- 
0-30     Amps.    \         ing    125    volts,    but    including    3-wire    circuits 

with  grounded    neutral  and  250  volts  between 
outside  wires. 


31-60     Amps. 

61-100  Amps. 
101-200  Amps. 
201-400  Amps. 
401-600  Amps. 


f  Cartridge  fuse 
\  (ferrule  contact). 


Cartridge  fuse  (knife  blade  contact). 


Not  over  600  Volts: 

>  Cartridge  fuse  (ferrule  contact). 


0-30 
31-60 


Amps. 
Amps. 


61-100  Amps. 
101-200  Amps. 
201-400  Amps. 


Cartridge  fuse  (knife  blade  contact) 


(68-f.) 


TABLE  No.  27 
SWITCH  SPACINGS  AND  SPECIFICATIONS 

[CODE  TABLE  I] 

Not  over  125  volts  D.  C.  and  A.  C. 
For  Switchboards  and  Panel  Boards. 

KNIFE  SWITCH  SPACINGS 

Minimum  separation  Minimum  break- 

of  nearest  metal  distance 

parts  of  opposite 
polarity 

10  amperes 3/4  in.  1/2  in. 

30  amperes 1  in.  3/4  in. 

60  amperes 1  1/4  in.  1         in. 

This  10-ampere  switch  must  have  ample  metal  for  stiffness, 
and  to  prevent  rise  in  temperature  of  any  part  of  more  than 
50  degrees  Fahrenheit  (28  degrees  Centigrade)  when  carrying 
30  amperes,  the  contacts  being  arranged  so  that  a  thoroughly 
good  bearing  at  every  point  is  obtained  with  contact  surface 
advised  for  pure  copper  blades  of  about  0.4  square  inch. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE     197 

[CODE  TABLE  II] 

Not  over  125  volts  D.  C.  and  A.  C. 
For  individual  switches: 

30  amperes  1  1/4  in.  1         in. 

60  and  100  amperes  1  1/2  in.  1  1/4  in. 

200  and  300  amperes  2  1/4  in.  2         in. 

400  and  600  amperes  2  3/4  in.  2  1/2  in. 

800  and  1,000  amperes  3         in.  2  3/4  in. 
The  300-ampere  switch  must  not  be  equipped  with  cut-out 
terminals. 

[CODE  TABLE  III] 

250  volts  only  D.  C.  and  A.  C. 
For  all  switches : 

30  amperes  1  3/4  in.          11/2  in. 

[CODE  TABLE  IV] 

Not  over  250  volts  D.  C.  nor  over  500  volts  A.  C. 
For  all  switches: 

30,  60  and  100  amperes         21/4  in.          2         in. 
200  and  300  amperes  2  1/2  in.          2  1/4  in. 

400  and  600  amperes  2  3/4  in.          2  1/2  in. 

800  and  1,000  amperes          3         in.          23/4  in. 

The  30-ampere  switch  must  have  ample  metal  to  prevent 
rise  in  temperature  of  any  part  of  more  than  50  degrees 
Fahrenheit  (28  degrees  Centigrade)  when  carrying  60  amperes, 
the  contacts  being  arranged  so  that  a  thoroughly  good  bearing 
at  every  point  is  obtained  with  contact  surfaces  advised  for 
pure  copper  blades  of  about  0.8  square  inch. 

The  300-ampere  switch  must  not  be  equipped  with  cut- 
out terminals. 

Cut-out  terminals  on  switches  for  over  250  volts  must  be 
designed  and  spaced  for  600- volt  fuses. 


198       QUESTIONS  AND  ANSWERS  ON  THE 

[CODE  TABLE  V] 
Not  over  600  volts  D.  C.  and  A.  C. 

For  all  switches: — 

30  and  60  amperes  4        inch  3  1/2 

100  amperes  4  1/2   "  4 

The  30-ampere  switch  must  have  ample  metal  to  prevt 
rise  in   temperature   of   any   part   of   more   than   50  de 
Fahrenheit  (28  degrees  Centigrade)  when  carrying  60  ampc 
the  contacts  being  arranged  so  that  a  thoroughly  good  bes 
at  every  point  is  obtained  with   contact  surfaces  advised 
pure  copper  blades  of  about  0.8  square  inch. 

Auxiliary  breaks  or  the  equivalent  are  recommended  fc 
D.  C.  switches  designed  for  over  250  volts,  and  must  be 
vided  on  D.  C.  switches  designed  for  use  in  breaking  current 
greater  than  100  amperes  at  a  voltage  of  over  250. 

For  three- wire  direct  current  and  three- wire  single  phf 
systems  the  separations  and  break  distances  for  plain  three- 
pole  knife  switches  must  not  be  less  than  those  required  in 
the  above  table  for  switches  designed  for  the  voltage  between 
the  neutral  and  outside  wires. 

[65-k,  and  April,  1912,  List  of  Fittings.] 

TABLE  No.  28 
SPACINGS  FOR  KNIFE  SWITCH  CUT-OUT  TERMINALS 

Not  over  600  volts  D.  C.  and  A.  C. 
For  all  switches : 

30  and  60  amperes  4  in. 

100  amperes  4  1/2  in. 


3  1/2  in 

4  in. 
(65-k.) 


TABLE  No.  29 
SWITCH  AND  Bus  SPACINGS  FOR  TABLETS  AND  PANEL  BOARDS 

The    following    minimum    distance    between    bare  live 
metal  parts  (busbars,  etc.)  must  be  maintained: 

Between  parts  of  opposite  polarity,  Between  parts  of 

except  at  switches  and  link  fuses.  same  polarity. 

When  mounted  on  When  held  free  in  At  link 

the  same  surface.  air.  fuses. 

Not  over  125  volts,     3/4  in.          1/2  in.  1/2  in. 

Not  over  250  volts,  1  1/4  in.          3/4  in.  3/4  in. 

Not  over  600  volts,  2         in.       1  3/4  in. 

At  switches  or  enclosed  fuses,  parts  of  the  same  polari 
may  be  placed  as  close  together  as  convenience  in  handli 
will  allow. 


OFFICIAL  NATIONAL  ELECTRICAL  CODE     199 

It  should  be  noted  that  the  above  distances  are  the  minimum 
allowable,  and  it  is  urged  that  greater  distances  be  adopted 
wherever  the  conditions  will  permit. 

The  spacings  given  in  the  first  column  apply  to  the  branch 
conductors  where  enclosed  fuses  are  used.  Where  link  fuses 
or  knife  switches  are  used,  the  spacings  must  be  at  least  as 
great  as  those  required  by  Nos.  65  and  67  (Tables  23  and  27). 

The  spacings  given  in  the  second  column  apply  to  the  distance 
between  the  raised  main  bars  and  between  these  bars  and  the 
branch  bars  over  which  they  pass. 

The  spacings  given  in  the  third  column  are  intended  to 
prevent  the  melting  of  a  link  fuse  by  the  blowing  of  an  adjacent 
fuse  of  the  same  polarity. 

Panel  boards  of  special  design  in  which  the  insulation  and 
separation  between  busbars  and  between  other  current- 
carrying  parts  is  secured  by  means  of  barriers  or  insulating 
materials  instead  of  by  the  spacings  given  above,  must  be 
submitted  for  special  examination  and  approval  before  being 
used.  (69-b.) 

Marking. 

Must  be  marked  where  the  marking  can  be  plainly  seen 
when  installed,  with  the  name  or  trade-mark  of  the  manu- 
facturer and  the  maximum  capacity  in  amperes  and  the 
voltage  for  which  the  board  is  designed.  (69-0.) 


TABLE  No.  30 

ClRCUITBREAKER  TEST 

Must  successfully  operate  three  times  with  two  minute 
intervals  intervening  without  incapacitating  the  breaker, 
the  conditions  of  testing  current  to  be  as  given  in  the  follow- 
ing table:  (66 -c.) 

Per  cent,  of  voltage       Minimum  available 


Current  rating  of 
breakers 
0  to  100  amperes  
101  to  300  amperes 

drop  in  test  circuit 
with  rated  current 
flowing 
2 
3 

capacity  of  supply 
system  not  including 
overload  capacity 
1000  amperes 
3000  amperes 

400  amperes. 

4 

4000  amperes 

500  amperes  

5 

5000  amperes 

(66-c.) 

200       QUESTIONS  AND  ANSWERS  ON  THE 

TABLE  No.  31 

INSULATION  TEST 

550  VOLTS  OR  LESS 

The  wiring  in  any  building  must  test  free  *rom  grounds; 
i.e.,  the  complete  installation  must  have  an  insulation 
between  conductors  and  between  all  conductors  and  the 
ground  (not  including  attachments,  sockets,  receptacles, 
etc.)  not  less  than  that  given  in  the  following  table: 

Up  to        5  amperes 4,000,000  ohms 

Up  to      10  amperes 2,000,000  ohms 

Up  to      25  amperes 800,000  ohms 

Up  to      50  amperes 400,000  ohms 

Up  to    100  amperes 200,000  ohms 

Up  to    200  amperes 100,000  ohms 

Up  to    400  amperes 50,000  ohms 

Up  to    800  amperes 25,000  ohms 

Up  to  1600  amperes 12,500  ohms 

The  test  must  be  made  with  all  cut-outs  and  safety 
devices  in  place.  If  the  lamp  sockets,  receptacles,  elec- 
troliers, etc.,  are  also  connected,  only  one-half  of  the  resist- 
ances specified  in  the  table  will  be  required.  (88.) 


OFFICIAL  NATIONAL  ELECTRICAL  CODE    201 

TABLE  No.  32 

NUMBER  OF  WIRES  IN  RIGID  CONDUIT, 
Following  table  is  inserted  for  convenience  in  estimating 
sizes  conduit  for  a  given  number  and  sizes  of  wires.     It  is 
not  a  Code  requirement,  except  in  so  far  as  wires  and  con- 
ductors must  be  installed  without  abrasion  of  the  insulation 


RULES  FOR 

RESUSCITATION 

FROM 

ELECTRIC  SHOCK 


Recommended  by 

Commission  on  Resuscitation  from 
Electric  Shock 


COURTESY  NATIONAL 
ELECTRIC  LIGHT  ASSOCIATION 


203 


COMMISSION    ON    RESUSCITATION    FROM    ELECTRIC 
SHOCK 

DR.  W.  B.  CANNON,  Chairman 

Professor  of  Physiology,  Harvard  University 
DR.  GEORGE  W.  CRILE 

Professor  of  Surgery,  Western  Reserve  University 
DR.  YANDELL  HENDERSON 

Professor  of  Physiology,  Yale  University 
DR.  S.  J.  MELTZER 

Head  of  Department  of  Physiology  and  Pharmacology, 

Rockefeller  Institute  for  Medical  Research 

DR.  EDW.  ANTHONY  SPITZKA 

Director    and   Professor   of  General    Anatomy,    Danie, 
Baugh  Institute  of  Anatomy,  Jefferson  Medical  College 

MR.  W.  C.  L.  EGLIN 

Past-President,  National  Electric  Light  Association 

DR.  A.  E.  KENNELLY 

Professor  of  Electrical  Engineering,  Harvard  University 

DR.  ELJHU  THOMSON 

West  Lynn,  Mass. 
MR.  W.  D.  WEAVER,  Secretary 

Editor,  Electrical  World 


COPYRIGHT,  1912 
National  Electric  Light  Association 


204 


TREATMENT  FOR  ELECTRIC  SHOCK 

An  accidental  electric  shock  usually  does  not  kill  at  once, 
but  may  only  stun  the  victim  and  for  a  while  stop  his 
breathing. 

The  shock  is  not  likely  to  be  immediately  fatal,  because : 

(a)  The  conductors  may  make  only  a  brief  and  imperfect 
contact  with  the  body. 

(6)  The  skin,  unless  it  is  wet,  offers  high  resistance  to  the 
current. 

Hope  of  restoring  the  victim  lies  in  prompt  and  continued 
use  of  artificial  respiration.  The  reasons  for  this  statement 
are: 

(a)  The  body  continuously  depends  on  an  exchange  of 
air,  as  shown  by  the  fact  that  we  must  breathe  in  and  out 
about  fifteen  times  a  minute. 

(6)  If  the  body  is  not  thus  repeatedly  supplied  with  air, 
suffocation  occurs. 

(c)  Persons  whose  breathing  has  been  stopped  by  electric 
shock  have  been  reported  restored  after  artificial  respiration 
has  been  continued  for  approximately  two  hours. 

The  Schafer,  or  "prone  pressure"  method  of  artificial 
respiration,  slightly  modified,  is  illustrated  and  described -in 
the  following  resuscitation  rules.  The  advantages  of  this 
method  are: 

(a)  Easy  performance ;  little  muscular  exertion  is  required. 

(6)  Larger  ventilation  of  the  lungs  than  by  the  supine 
method. 

(c)  Simplicity;  the  operator  makes  no  complex  motions 
and  readily  learns  the  method  on  first  trial. 

(d)  No  trouble  from  the  tongue  falling  back  into  the  air 
passage. 

(e)  No  risk  of  injury  to  the  liver  or  ribs  if  the  method  is 
executed  with  proper  care. 

A  id  can  be  rendered  best  by  one  who  has  studied  the  rules 
and  has  learned  them  by  practice  on  a  volunteer  subject. 


205 


INSTRUCTIONS  FOR  RESUSCITATION 

FOLLOW  THESE  INSTRUCTIONS  EVEN  IF  VICTIM  APPEARS 
DEAD 


I.  Break  the  Circuit  Immediately 

1.  With  a  single  quick  motion  separate  the  victim  from 
the  live  conductor.     In  so  doing  avoid  receiving  a  shock 
yourself.     Many  have,  by  their  carelessness,  received  injury 
in  trying  to  disconnect  victims  of  shock  from  live  conductors. 

OBSERVE  THE  FOLLOWING  PRECAUTIONS 
(a)  Use  a  dry  coat,  a  dry  rope,  a  dry  stick  or  board,  or 
any  other  dry  non-conductor  to  move  either  the  victim  or  the 
wire,  so  as  to  break  the  electrical  contact.  Beware  of  using 
metal  or  any  moist  material.  The  victim's  loose  clothing, 
if  dry,  may  be  used  to  pull  him  away;  do  not  touch  the 
soles  or  heels  of  his  shoes  while  he  remains  in  contact — the 
nails  are  dangerous. 

(6)  If  the  body  must  be  touched  by  your  hands,  be  sure 
to  cover  them  with  rubber  gloves,  mackintosh,  rubber 
sheeting  or  dry  cloth;  or  stand  on  a  dry  board  or  on  some 
other  dry  insulating  surface.  If  possible,  use  only  one  hand. 
If  the  victim  is  conducting  the  current  to  ground,  and  is 
convulsively  clutching  the  live  conductor,  it  may  be  easier 
to  shut  off  the  current  by  lifting  him  than  by  leaving  him 
on  the  ground  and  trying  to  break  his  grasp. 

2.  Open  the  nearest  switch,  if  that  is  the  quickest  way  to 
break  the  circuit. 

3.  If  necessary  to  cut  a  live  wire,  use  an  ax  or  a  hatchet 
with  a  dry  wooden  handle,  or  properly  insulated  pliers. 

n.  Send  for  the  Nearest  Doctor 

This  should  be  done  without  a  moment's  delay,  as  soon 
as  the  accident  occurs,  and  while  the  victim  is  being  removed 
from  the  conductor. 

The  Doctors  entered  on  page  205  are  recommended: 


206 


INSTRUCTIONS  FOR  RESUSCITATION       207 


Telephone  Call. 


Name 

Address 

Telephone  Call. 


Name 

Address 

Telephone  Call 


Name 

Address 

Telephone  Call 


208       INSTRUCTIONS  FOR  RESUSCITATION 

in.  Attend  Instantly  to  Victim's  Breathing 

(1)  As  soon  as  the  victim  is  clear  of  the  live  conductor, 
quickly  feel  with  your  finger  in  his  mouth  and  throat  and 
remove  any  foreign  body  (tobacco,  false  teeth,  etc.)     Then 
begin  artificial  respiration  at  once.     Do  not  stop  to  loosen 
the  patient's  clothing;  every  moment  of  delay  is  serious. 

(2)  Lay  the  subject  on  his  belly,  with  arms  extended  as 
straight  forward  as  possible,  and  with  the  face  to  one  side, 
so  that  the  nose  and  mouth  are  free  for  breathing  (see  Fig.  1). 
Let  an  assistant  draw  forward  the  subject's  tongue. 


FIG.  1. — Inspiration;  Pressure  Off. 

If  possible,  avoid  so  laying  the  subject  that  any  burned 
places  are  pressed  upon. 

Do  not  permit  bystanders  to  crowd  about  and  shut  off 
fresh  air. 

(3)  Kneel  straddling  the  subject's  thighs  and  facing  his 
head;  rest  the  palms  of  your  hands  on  the  loins  (on  the 
muscles  of  the  small  of  the  back)/   with  thumbs  nearly 
touching  each  other,  and  with  fingers  spread  over  the  lowest 
ribs  (see  Fig.  1). 

(4)  With  arms  held  straight,  swing  forward  slowly  so  that 
the  weight  of  your  body  is  gradually  brought  to  bear  upon 
the   subject    (see  Fig.    2).     This   operation,    which  should 
take  from  two  to  three  seconds,  must  not  be  violent — internal 
organs  may  be  injured.     The  lower  part  of  the  chest  and 
also  the  abdomen  are  thus  compressed,  and  air  is  forced  out 
of  the  lungs. 


INSTRUCTIONS  FOR  RESUSCITATION       209 

(5)  Now  immediately  swing  backward  so  as  to  remove 
the  pressure,  but  leave  your  hands  in  place,  thus  returning 
to  the  position  shown  in  Fig.  1.     Through  their  elasticity, 
the  chest  walls  expand  and  the  lungs  are  thus  supplied  with 
fresh  air. 

(6)  After  two  seconds  swing  forward  again.     Thus  repeat 
deliberately  twelve  to  fifteen  times  a  minute  the  double 
movement  of  compression  and  release — a  complete  respira- 
tion in  four  or  five  seconds.     If  a  watch  or  a  clock  is  not 
visible,  follow  the  natural  rate  of  your  own  deep  breathing — 
swinging  forward  with  each  expiration,  and  backward  with 
each  inspiration. 


/IG.  2. — Expiration;  Pressure  On. 

While  this  is  being  done,  an  assistant  should  loosen  any 
tight  clothing  about  the  subject's  neck,  chest,  or  waist. 

(7)  Continue  artificial  respiration  (if  necessary,  two  hours 
or  longer),  without  interruption,  until  natural  breathing  is 
restored,  or  until  a  physician  arrives.     Even  after  natural 
breathing  begins,  carefully  watch  that  it  continues.     If  it 
stops,  start  artificial  respiration  again. 

During  the  period  of  operation,  keep  the  subject  warm 
by  applying  a  proper  covering  and  by  laying  beside  his  body 
bottles  or  rubber  bags  filled  with  warm  (not  hot)  water. 
The  attention  to  keeping  the  subject  warm  should  be  given 
by  an  assistant  or  assistants. 

(8)  Do  not  give  any  liquids  whatever  by  mouth  until  the 
subject  is  fully  conscious. 

14 


210      INSTRUCTIONS  FOR  RESUSCITATION 

FIRST  CARE  OF  BURNS 

When  natural  respiration  has  been  restored,  burns,  if 
serious,  should  be  attended  to  until  a  doctor  comes. 

A  raw  or  blistered  surface  should  be  protected  from  the 
air.  If  clothing  sticks,  do  not  peel  it  off — cut  around  it. 
The  adherent  cloth,  or  a  dressing  of  cotton  or  other  soft 
material  applied  to  the  burned  surface,  should  be  saturated 
with  picric  acid  (0.5  per  cent.).  If  this  is  not  at  hand,  use 
a  solution  of  baking  soda  (one  teaspoonful  to  a  pint  of  water), 
or  the  wound  may  be  coated  with  a  paste  of  flour  and  water. 
Or  it  may  be  protected  with  a  heavy  oil,  such  as  machine 
oil,  transformer  oil,  vaseline,  linseed,  carron  or  olive  oil. 
Cover  the  dressing  with  cotton,  gauze,  lint,  clean  waste,  clean 
handkerchiefs,  or  other  soft  cloth,  held  lightly  in  place  by  a 
bandage. 

The  same  coverings  should  be  lightly  bandged  over  a  dry, 
charred  burn,  but  without  wetting  the  burned  region  or 
applying  oil  to  it. 

Do  not  open  blisters. 


INDEX 


PAGE 

Acid  fumes,  wires  subject  to 67 

Accessibility  of  auto-starters 92 

cut  outs,  branch 94 

main 59,  94 

generator  conductors 14 

grounds  on  metallic  protective  system 59 

junction  boxes  on  armored  cable 83 

lightning  arrestors 15 

switches,  main 59 

Arc  lamps,  construction 51,  52,  53 

cut-out  required 51 

hanger  board  required « 53 

incandescent  lamps  as  resistance 51 

installation 51,  52,  53 

resistance 51 

size  branch  conductor  for 51 

spark  arrestor,  when  required 51 

spark  arrestor,  not  required 52 

wiring,  protection  of 52 

Arc  lamp,  moving  picture  machine 113 

Arc  lamps,  series,  attachment  to  gas  fixtures  forbidden 53 

concealed  wiring  not  permitted 52 

cracked  globes  not  permitted 53 

enclosed,  required 53 

isolation  of 52 

rubber  covered  wire  required 52 

size  mesh  allowed  for  wire  netting 53 

ppark  arrestor  required 53 

switch,  type  required 52,  53 

wire  spacings 52 

Armored  cables.     See  Cables. 

Auditorium  lights 106 

Auto-starters.     See  Rheostats. 

Batteries,  storage  and  primary 19,  20 

Binding  screws  not  to  bear  strain 131 

Blocks,  wood,  for  fixtures 124 

for  insulators 30 

for  switches 94 

Border  lights 107,  108 

Boxes,  junction,  accessibility  of  armored  cable 83 

211 


212  INDEX 

Boxes,  support  of  cables  in 79 

supporting  risers  in .  .  . 79 

Boxes,  outlet,  armored  cable  installation 84 

omitted 82 

broken  plaster  not  permitted  at 58 

conduit,  construction,  lined 80,  81 

unlined 80,  81 

when  required 79,  80 

installation 79,  80,  81 

covers,  porcelain  for 81 

type  acceptable 81 

installation,  concealed  work 72 

joints  in 79 

Boxes,  portable  plugging,  construction 109 

Boxes,  reel,  moving  picture,  construction 1 13 

Boxes,  switch,  outline  lighting  construction 115 

Bunch  lights,  construction 108,  109 

Bus  bars,  bare 14 

Bushings,  armored  cable,  omitted  on 83 

brick  walls,  through 58 

entrance,  light,  heat  and  power 29 

signal  system 41 

generator,  type  obligatory 11 

required  conduit  work 80 

electric  signs 116 

Cabinets,  approved  kind 100,  101 

construction 100,  101 

markings 100 

service,  conduit  entering 33 

spacings 100,  101 

Tables  27  and  29 196,  197,  198 

spacings  for  link  fuses  in 101 

switches  ia1 101 

wires  entering 61,71 

wooden,  construction 100,  101 

not  permitted  on  conduit  system 100 

Cables,  supported  in  junction  boxes 79 

Cables,  armored,  bends  allowed 82 

construction 82,  83 

grounding 83,  84 

installation 82 

joints 82 

Cables,  armored  lead,  construction 82 

damp  places,  required 83 

fireproof  buildings,  when  required 83 

outline  lighting 115 

Cables,  elevator,  insulation 131 

Table  17 188 

smallest  conductor  permitted 131 

Cables,  lead  sheathed,  type  letter 13 


INDEX  213 

Cables,  required  for  high  potential  motors 17 

Cables,  theater,  feeder,  required  for  borders 107 

insulation  required,  Table  16 186 

Cables,  varnished  cambric 166 

Canopies 126 

Capacity  allowed,  aluminum  wire 57 

alternating  current  (rubber  covered  wire) 18 

Table  1 167 

rubber  covered  wire,  Table  1 167 

slow  burning  wire 58 

Table  1 167 

slow  burning  weather-proof  wire 58 

Table  1 167 

plugging  box  receptacle 109 

Care  and  attendance 16 

Note  8 17 

Christmas  tree  lights 118 

Circuits,  signal  systems,  installation 41,  43,  47 

metallic,  required 41 

wattage  limits,  2-wire 58 

3- wire 59 

Circuit  breakers,  adjusting  limits 96,  97 

installation 97 

markings  required 97 

on  generators 11,  12,  96,  97 

operation  of 96,  97 

test,  breaking,  Table  30 199 

used  as  service  switch 93 

Cleats,  construction 68 

Table  21 192 

installation 65,  70 

Code,  enforcement 3 

how  made 1 

originator 4 

Competent  operator  required,  central  stations 16 

theaters  and  moving  picture  shows 112 

Concealed  wiring,  knob  and  tube 71,  72 

Condensers  and  reactive  coils 45 

Conductors,  aluminium ' 168 

distance  between,  at  switchboard 14 

inside  wiring,  kind  permitted 31,  43,  57,  67,  70 

Table  8 174,  175 

installation  generator  to  switchboard 14 

size  branch,  for  arc  lamp 51 

smallest  size,  moving  picture  machine 113 

spacing  tablet  board,  Table  29 198 

stranded  in  fixture  work 123 

support  of  in  vertical  conduit 79 

underground,  requirements 36 

Conduit,  brass,  not  permitted 81 


214  INDEX 

Conduit,  rigid  metal,  accessibility  of  ground  on 59 

bends 80 

bonding  high  tension  motor  leads 14 

central  stations,  lined  required 14 

circuits,  number  allowed 78 

construction 78,  80,  81 

curve,  shortest  allowed 80 

electric  signs,  required 117 

entering  cabinets 33,  77,  78 

exposed  to  weather 33 

Note  15 34 

fastening  to  boxes 80 

fittings,  installation 78,  80 

galvanized  pipe  as 82 

grounding,  interior,  Note  26 77,  83,  84 

installation  requirements 77 

outlet  boxes  required 79 

elevator  shafts 68 

knob  and  tube  work 60,  63,  69 

marine  work 157 

theaters  and  moving  picture  establishments 106,  107 

smallest  size  permitted 78 

support  of 78 

support  of  risers  in  vertical 79 

wires,  drawn  before  completion  of  mechanical  work 78 

wires  of  different  systems  in 78 

Conduit,  flexible  metallic,  installation 82 

requirements , 82 

Connectors,  pin  plug 109 

Covers,  outlet  box,  type  acceptable 81 

porcelain,  for  outlet  boxes 81 

switch  box,  damp  places 94 

waterproof,  required  for  generators  and  motors 17 

Cranes,  electric,  collectors,  construction 136 

conductors,  insulation  resistance 135 

controlling 136 

cut  outs  required 137 

grounding 137 

resistance,  protection  of 137 

wire,  bare,  permitted 135 

collector,  size  required 136 

support  of 136 

distance  from  surface 136 

installation 135,  136 

rubber  covered,  required 137 

slow  burning,  required 135 

smallest  size,  permitted 135 

spacings 136 

Cut  outs,  fuse  limits  in  branch 61 

location 59,  94 

omitted  in  service 94 


INDEX  215 

required  at  change  of  wire 93 

at  arc  lamp 51 

at  electric  crane 137 

at  marine  work 156 

at  mercury  vapor  lamp 120 

at  outline  lighting 115 

at  signal  system 41,  42,  44 

signal  system,  construction 42 

single  pole,  omitted  on  generator 12 

wattage  limits,  fixture  work 123 

outline  lighting 115 

theater  work 106 

Distance,  arc  lamps  to  sidewalk 51 

between  supports,  electric  cranes 135 

electric  signs 116 

inside  work,  concealed 71 

open 65,  70 

outline  lighting 115 

between  wires,  inside  work,  concealed 65 

open 65 

from  last  line  support  to  rosette 70 

from  surface  wired  over,  electric  cranes 135 

electric  signs 116 

inside  work,  concealed 65 

open 65 

outline  lighting 114-115 

Electric  fans,  ceiling 18,  19 

fuse,  number  on  one  set  of 18 

portable 19 

Emergency  lights,  what  are 105 

wiring  for 105 

Exit  lights,  control  of 106 

forbidden  on  stage  circuits 106 

fuses  on 106 

Fire  proof  building,  armored  lead  cable,  when  required 83 

canopies  in 126 

Fittings,  conduit,  installation 78 

terminal 79 

Fixtures,  burs  and  pins  must  be  removed 126 

canopies,  flat  when  permitted, 126 

fuses  not  permitted  in 126 

insulated,  required 126 

insulated,  not  required 126 

construction 125,  126 

cu^  out,  wattage  limits 123 

flexible  cord  permitted  in 123 

flexible  tubing  at  outlets 124,  125 

fuse,  six  ampere  permitted 123 


216  INDEX 

gas  lighting  systems  on 125 

grounds  free  from 125,  127 

hickeys  required 124 

insulating  joints,  construction 125 

required 124 

not  required 125 

receptacles,  exposed  terminals 126 

subject  to  heat 127 

sockets,  attachment  of 126 

testing 125,  127 

Table  31 200 

voltage,  maximum 123 

watertight,  required 125 

wires  of  different  systems  in 124 

wiring,  exposed,  on 125 

wooden  blocks  required .  .  . 124 

wooden,  armored  conductors  required 127 

construction 127 

when  approved 127 

Fixture  wire,  flex  cord  approved 123 

tinned,  required 123 

ordinary  rubber  covered  permitted 123 

slow-burning  wire,  on 124,  127 

smallest  size  permitted 123 

stranded,  approved 123 

required 124 

test 124 

Flexible  cord,  electric  heaters,  type  for 119 

fan  motors  for 19,  130 

fixtures  permitted  in 123 

heat,  subject  to 127,  135 

insulation  requirements,  Tables  10-18 178-189 

knots  in,  required 131 

long  pendants,  type  permitted 131 

portable  lamps,  type  for 131 

Tables  for 178-185 

theater  work,  type  required 110,  111 

show  cases,  type  required 130 

voltage  limits 130 

when  "Type  C"  is  permitted 130 

when  not  permitted .  .....  .... 131 

wooden  fixtures,  type  required 127 

Flexible  tubing,  construction 72,  73 

fished  wires  in 71 ,  72 

requirements  in  fixture  work 72,  124,  125 

in  knob  and  tube,  open 67,  69,  72 

in  knob  and  tube,  concealed 67,  72 

in  outline  lighting .    114,  115 

in  signal  systems 42 

when  permitted 71,  72 


INDEX  217 

Foot  light  construction 107 

Fuses,  canopy,  not  permitted 126 

change  of  wire,  required 93 

circuits,  branch  in  mills 97 

house. 59,  60 

cut  outs,  branch,  limits  in 61 

electric  signs  55-volt  circuits 116 

fixture  wire,  six  ampere  for 123 

generator 11,  12 

ground  detector,  for 15 

grounded  neutral 59,  60 

inside  work.  (See  Cut  outs) 59,  98 

motors  limited  on  one  set  of 18 

neutral  wire,  omitted  on 59 

non-grounded  neutral 60 

on  theater  exit  lights 106 

Out-buildings,  omitted  on 93 

pilot  light 14,  15 

potential  transformer 15 

rosette,  double  pole 99 

signal  systems,  required  on 41,  42,  44,  45 

theater  work 106 

Fuses  enclosed.  (Cartridge  and  Plug),  cartridge  refilling 98 

construction  (cartridge) 98 

(plug),  Table  24 193 

dimensions,  Table  25 194,  195 

ferrule  contact,  Table  25 194,  195 

heat  limits 98 

in  mills,  large 98 

labels,  colors  required 98 

knife  contact,  Table  25 194,  195 

markings 98 

motor,  A.  C.  required 16,  17 

plug,  refilling 98 

Fused  link,  branch  circuits  in  large  mills 97 

contact  tips 97 

markings  required 97 

spacings 98,  101 

Table  23 51 

when  permitted 97 

Gas  lighting  on  fixtures 125 

Generators,  bushings,  type  permitted 11 

circuit  breakers 11,  12,  93,  96,  97 

cut  outs,  single  pole  when  permitted 12 

frame,  grounding  required 12 

insulation  of 12 

fuses 11,  12 

guards  for  high  potential 13 

high  potential,  wiring 13,  14 


218  INDEX 

location  of 11 

name  plate  required 11 

terminal  blocks,  kind  permitted 11 

wiring,  Note  7 16 

Grounding,  armored  cable 83,  84 

conduit 83,  84 

conduit,  not  required 70 

electric  crane  motors • 137 

flexible  metallic  conduit 82 

generator  frames 12 

inside  wires 32,  33 

lightning  arrestors,  central  station 16 

electric  cars 150 

mercury  vapor  lamps 120 

metal  moulding 85 

metallic  protective  systems 83 

Note  23 69 

grounded  neutral  systems 59,  601 

neutral  wire 31,  32,  33,  59,  60 

outside  wires 31,  33 

secondary  wires 31,  32,  33 

signal  system  wires 45,  46 

three-phase  wires 32 

transformers 23,  25,  33 

wireless  telegraph 46,  47 

Grounding  secondaries,  Amer.  Institute  of  Elec.  Engs.  on 5 

Ground  detectors  required 15 

Grounded  neutral  systems 59,  60 

Guards,  incandescent  lamps,  required  for 110,  111,  127 

high  potential  generators 13 

motors 13 

Strip  required  for  wires 69 

Hanger  boards,  construction 53 

Heat,  fixtures  subject  to 127 

wires  subject  to 67 

Heaters,  electric,  approved  stand  required,  flatiron,  etc 118 

car 147 

conductor,  attachment  of 119 

conductor,  type  required 119 

Table  14 184 

installation   118,  119 

name  plate  required 119 

Insulators,  cleats,  construction,  Table  21 192 

installation 67,  68 

use  of 44,  68 

knobs,  installation «44,  68 

outside  work,  when  permitted  for 30 


INDEX  219 

knobs,  solid,  construction. 65,  68 

Table  20 191 

not  permitted 68 

permitted 68 

required  at  end  of  runs 70 

split,  construction 68 

required 68 

petticoat,  outside  ;work,  required 30 

distance  apart 30 

Insulation  resistance  of  completed  buildings 41 

Table  31 200 

Joints,  armored  cable 82 

outlet  boxes,  in 79,  82 

streamers  and  festoons 110 

wire,  inside  work 29 

marine  work 156 

outside  work 29 

wood  moulding 73 

Joints,  insulating,  construction  of 125 

required 124 

when  omitted 125 

Knobs.     See  Insulators. 

Knots,  inflexible  required  in  socket  and  rosette 131 

Lamps,  arc.     See  Arc  Lamps. 

Lamps,  incandescent  allowed  on  2-wire  ordinary  house  circuit.  .  .  .  123 

allowed  on  3- wire  ordinary  house  circuit 60,  61 

arc  lamps,  incandescent,  as  resistance  for 51 

rheostats,  as  resistance  for 80 

series 53,  54,  90 

Lamps,  mercury  vapor,  cut  out  required 120 

number  on  each 120 

grounding 120 

installation 119,  120 

resistance,  protection  of 120 

voltage  limits 120 

Lamps,  portable,  flexible  cord,  type  permitted 127 

guard  required 127 

Leather  heads,  use  of  permitted 68 

Life  hazard 5 

Light -s  arc.     See  Arc  Lamps, 
car.     See  Railway  Systems, 
signal.     See  Marine  Work, 
theater.     See  Theater  Wiring. 

Lighting,  outline,  armored  lead  cable  required 115 

box,  construction  of  switch 115 

cut  out  installation 115 

required 115 

wattage  limits 115 


220  INDEX 

flashers,  installation 115 

flexible  tubing,  installation 114,  115 

moulding  not  permitted 114 

receptacles,  limit  on  circuit 115 

type  required 116 

sockets,  keyless,  required 116 

switch,  installation 115 

required 115 

wattage  limit  on  single  cut  out 115 

wires  soldered  to  receptacles 1 16 

kind  required  in  conduit 115 

Lighting  system,  decorative,  Christmas  tree 118 

limits  specified 118 

special  permission  necessary 118 

Lightning  arrestors,  accessibility  of 15 

approved,  required  for  central  stations 16 

street  railway 150 

grounding 16 

insulation  resistance  required 16 

number  and  location 15 

signal  system 44 

Main  block 59,  98 

Marine  wiring,  bonding  of  cabinet  boxes 157 

brass  screws  required 157 

conduit,  A.  C.  circuits  in 157 

number  of  .circuits  in 158 

required 157 

requirements 157 

cut  outs,  wattage  limits 156 

waterproof  required 156 

fittings,  conduit  requirements 157 

fixtures,  mounting 160 

protection 160 

freight  compartments,  central 156 

generator  frames,  insulation 155 

guards  required  for  lamps 160 

joints 156 

moulding,  wood  construction 157 

installation 157 

type  wire  required 156 

test  wire  required 156 

motors,  installation  requirements 161 

open  work  not  permitted 155 

portable  conductors 158,  159 

Table  18 189 

resistance  boxes,  installation 159 

rubber  tubing,  thickness  required 158 

signal  lights 160 

sockets. . .                                                                                           160 


INDEX  221 

stuffing  tubes  required 158 

switches,  deck 159 

switchboard,  insulation  of  wires  at 159 

special  requirements,  conductors 159 

wood  not  acceptable 159 

Note 159 

tell-tale  board  required 160 

vapor-proof  globes  required 160 

wire,  allowable  carrying  capacity 155 

bell 161 

conduit 157 

fixture 160 

largest  solid,  permitted 155 

smallest  solid,  permitted 155 

stranded,  construction 159 

Meters,  installation 60 

Motors,  alternating  current,  allowable  capacity  of  wiring 18 

overload  capacity  of  circuits 18 

variable  speed,  markings 19 

wire  capacity  starting 18 

wiring  for  varying  speed 18 

care  and  attendance 16 

circuits,  electrical  protection  of 16 

enclosed,  recommended  for  dusty  places 17 

fans 19 

frame,  grounding  when  required 17 

insulation 17 

high  potential  wiring 17 

marine 161 

name  plate  required 16 

number  permitted  on  one  set  fuses 18 

rating 16 

single-phase,  fuses  required 16 

stage  curtain  ironclad  type  obligatory 108 

switches,  indicating  required 17 

single-pole  when  permitted 17 

variable  speed,  starting 17 

water-proof  cover  obligatory 17 

wiring  capacity,  Table  1 168 

Moving  picture  establishment  wiring 113,  114 

arc  lamp,  construction 113 

automatic  shutter 113 

films,  extra 113 

under  examination 113 

machine  installation  of 114 

operation  of 114 

motor  driven  machine  permitted 114 

operator,  competent,  required 112 

reel  boxes,  construction 113 

rheostat,  installation 113 

wire,  smallest  size  permitted  for  machine 113 


222  INDEX 

Moulding  metal,  construction 84,  85 

grounding 85 

installation 84 

Moulding,  wooden,  circuits,  number,  in  one  groove 73 

conductors  A.  C.,  in  same  groove 73 

construction 73,  74 

damp  places,  not  permitted  in 73 

outline  lighting,  not  permitted  in. . .  : 114 

use  of 73 

wire,  rubber  covered,  required 73 

Nails  and  leather  heads,  use  of  permitted 68 

Open  wiring.     Section  6,  division  1   57,  71 

Outlets,  flexible  tubing  required  at 72 

open  spaces  not  permitted  at 58 

stage  and  gallery 108 

terminal  fittings  for  fixture 79 

Note  28 79 

Outline  lighting.     See  Lighting  Outline. 

Panel  boards,  tablet  and,  construction 101,  102 

marking  required 101 

spacings 102 

Table  29 198 

Pilot  lights,  fuses  for 14 

Plates,  dust-proof,  when  required 89 

Plates,  outlet,  used  instead  of  boxes 80 

when  required 80 

Plates,  switch,  push  buttons  forbidden  on 93 

Plugs,  attachment 98 

ordinary  fuse,  Table  23 193 

stage 108 

Pockets,  stage 108 

Pole  line,  high  tension 34,  36 

Note  16 34 

low  tension 30 

railways 141 

Precautions  in  damp  places 5 

Protecting  wires  from  mechanical  injury 69 

Protective  devices  on  signal  circuits 44 

Railway  systems,  automatic  control 148 

cabinet,  cut  out,  material  required 143 

cabinet  used  as  outlet  boxes 148 

car  body,  protection  of 142,  143 

cars  not  to  be  left  in  electrical  connection 152 

circuits,  heater,  minimum  size  wire 143 

circuits,  lighting  and  motor 151 

installation...                                                                     147 


INDEX  223 

minimum  size  wire 143 

over  fused 145 

stationary  motor,  bonding 151 

circuit  breakers  must  be  approved 145 

clusters,  installation 147 

must  be  approved 147 

conductor  connections,  construction 144 

conduit,  burrs  in 150 

installation 145,  146 

size  acceptable 145 

third  rail  not  grounded 146 

connections,  bonding  of 151 

controller,  installation 149 

current  not  to  be  taken  from  railway  circuits 151 

cut  out  connections,  controlling 151 

installation 143,  144 

location 145 

required 145 

enclosure  for  air  pump  and  motor 148 

feeder  distribution,  centering 152 

fittings,  installation 145,  146 

flexible  cord  permitted  in  car  houses 152 

fuses  may  be  omitted 145 

general  rules  applying 152 

ground  return,  code  requirements 142 

guard  wires,  insulation 141 

hangers,  trolley,  required 150 

distance  apart 150 

heaters,  approved  required 147 

construction 147 

installation 147 

insulation  between  trolley  and  ground 141 

knob  and  tube  work  permitted 147,  148 

permitted 146 

tacking  wires  in 1 50 

rails,  bonding 151 

receptacles,  approved  required 147 

installation 147 

resistance,  insulation 149 

lead  wires,  capacity 143 

smallest  size 143 

soldered  connections  omitted 144 

soldered  connections  required 144 

switches,  connections  controlling 151 

installation 145 

type  required 145 

lamps,  separate,  cut  out  required 151 

separate  switch  required 151 

wattage  limit  of  each 147 

lightning  arrester,  location 150 

ground  wire,  smallest  size .  150 


224  INDEX 

motor,  circuits,  main 148,  149 

cut  outs  required 151 

installation 149 

lead  wires,  carrying  capacity 143 

switch  separate,  required 150,  151 

moulding  accessibility 150 

backing  omitted 146 

construction 146 

installation 146,  147 

switches,  emergency 150,  151 

snap,  permitted 145 

switch  box  construction 145 

wires,  feed  division  of 141 

feed,  protecting  at  crossings 141 

fixture  permitted 144 

rubber  covered,  special  required 144 

trolley,  protection  at  crossings 141 

smallest  size  permitted 141 

strain  requirements 141 

trolley  lead  capacity J  43 

Receptacles,  eloctric  sign 117 

outline  lighting 115,  116 

ordinary 106,  107 

Receptacles,  stage,  approved 108 

capacity  of  arc  and  incandescent 108 

control  of 108 

wiring  requirements 108 

Resuscitation  from  electric  shock 203 

Rheostats,  construction 89,  90,  91 

dust  plate  required 89 

incandescent  lamps  as  resistance 90 

installation 89,  90 

markings  required 90 

maximum  difference  of  potential 89 

no  voltage  release  required 90 

overload  release  required 91 

resistance  and  contact  plates,  wire  required 90 

test 91 

auto-starting,  construction 91,  92 

installation 92 

use  of 91 

moving  picture  machine  installation 113 

Risers,  support  of,  in  conduit 79 

Rosettes,  construction 99 

fused 99 

link  fused  permitted 97 

Sections,  one,  central  stations,  generators,  motors,  storage  batteries  11-20 

two,  transformers. 23-26 

three,  outside  work 29-36 

four,  signal  systems 141-147 


INDEX  225 

five,  constant  current  systems 52-54 

six,  division  one,  knob  and  tube  work 65-74 

two,  metallic  protective  systems 77-85 

three,  rheostats 89-91 

auto-starters 91,  92 

switches 92-96 

circuit  breakers 96,  97 

fuses 97,  98 

rosettes 99,  100 

cabinets 100,  101 

panel  boards 101,  102 

four,  theater  wiring 105-112 

moving  picture 113,  114 

outline  lighting 114,  115,  116 

electric  signs 116, 117,  118 

decorative  lighting 118 

electric  heaters 118,  119 

mercury  vapor  lamps 119,  120 

five,  fixtures 124-127 

sockets 127-130 

flex  cord 130,  131 

six,  electric  cranes.' 135,  136,  137 

seven,  electric  railway  systems 141-152 

eight,  marine  work 155-161 

nine,  Tables  (1-32) 167-201 

Signal  systems,  bushing,  entrance  wires  in  single 41 

circuits,  all  metallic,  required 41 

condensers 45 

cut  outs,  entrance,  location 42 

for  each  wire  required 41 

type  required,  telegraph  circuits 44 

flex  tubing 42 

fuses,  location,  telegraph  systems 44 

required  on  protector 45 

fuse  block,  construction 42 

inside  wiring,  questions  applying 42 

heat  coils 45 

instrument,  installation 42,  44 

lightning  arrestor,  grounding 44 

protectors,  marking  required 45 

reactive  coils 45 

subject  to  code 43 

sneak  currents 45 

staples 42 

wires,  cabled,  exceptions  for 43 

cross  arms  on 43 

ground,  installation 45,  46 

iron 43 

shafts  in 42 

on  buildings 43 

smallest  size. . .  42 


226  INDEX 

smallest  size,  ground 45 

kind  supplying  current  to  apparatus 44 

underground 43 

when  separate  tube  is  required 42 

Signs,  electric,  bushings  required 116 

conduit  or  cable  required 117 

construction 117 

corrosion 117 

cut  out,  wattage  limits  on  final 116 

fuse  limits  on  55-volt  circuit 116 

open  work,  when  permitted 116,  117 

receptacles,  spacings 1 16,  117 

type  required 117 

switches,  single  pole 118 

transformers,  installation 116 

wire,  smallest  size 118 

supply 118 

type  required 1 18 

wiring 116,  117,  118 

wood 117 

Smallest  size  wire  permitted,  electric  signs  on 118 

elevator  control,  conductor  for 131 

fixtures 123 

ground  detector 15 

grounding,    alternating    current,    lightning    arrestors,    central 

station 16 

electric  cars 150 

metal  moulding 85 

metallic  protective  system 84 

Note  23 69 

neutral,  direct  current,  central  station 32 

signal  system,  protective  devices 45 

three-phase  systems 32 

wireless  telegraph  apparatus 46 

interior  work 57 

marine  work 155,  158 

moving  picture  machine  arc  lamp 113 

railway  systems 143,  151 

signal  systems 42 

theater  work 108,  131 

Sockets,  construction 128,  129 

markings 128 

use  of  in  hazardous  places 128 

used  on  pipe  pendants 128 

candelabra 129 

double  ended 129 

key 128 

keyless 128 

miniature 129 

weather-proof 130 

Soldering  required,  electric  sign  receptacles 117 


INDEX  227 

joints,  wire 29,  110,  156 

outline  lighting  receptacles 116 

railway  systems . 144,  152 

rheostats 90,  92 

signal  systems 46 

switch  lugs 96 

theater  receptacles 106,  107,  110 

wires  stranded 67,  69,  96 

Spacings,  cabinets,  metal 115 

wood 100,  101 

fuse  enclosed,  Table  25 194,  195 

link 98 

Table  23 193 

insulator  pins 43 

panel  boards 101,  102 

Table  29 198 

receptacles,  electric  signs 116,  117,  118 

rheostats 90,  111,  112,  137 

switch 95,  96 

Tables  27,  28 196,  198 

switchboard  from  ceiling 15 

wall 15 

transformers  from  wall 24 

wire,  central  stations 13 

electric  crane 135,  136 

electric  railway  car 147,  148 

electric  signs 117 

inside  work,  concealed 65 

open 65,  70 

outline  lighting 114,  115 

outside  work 29,  30 

series  arc 52 

storage  batteries 20,  65 

Spark  arresters,  construction 51 

not  required 52 

required 53 

Splices  and  joints  in  wire 29,  73,  156 

Subject  to  code,  burglar  alarm  service 43 

electric  bells  inside  buildings 42,  43 

Read  Low  Voltage  Transformer 25 

electric  call  bell,  outside 41,  43 

fire  alarm  companies.     (See  Explanation  of  Section  4,  page  41) , 

35,  41,  43 

telegraph  companies 41 ,  43 

telephone  companies 41 ,  43 

Switches,  accessibility 59,  92 

construction,  knife 94,  95 

double  brake,  auxiliary  required 95 

double  throw,  installation 93 

electric  sign,  single  pole  not  permitted 118 

grouping 93 


228  INDEX 

installation 92,  93,  94,  95 

Note  34 95 

oil,  dust-proof  cases  required 92 

outline  lighting,  contact  required 115 

installation 115 

rating  for  D.  C.  and  A.  C 95 

single  pole  on  neutral  wire 94 

service,  circuit  breaker  as 93 

indicating  required 94 

location 93 

must  disconnect  all  wires 95 

series  arc,  construction 53 

installation 52 

type  required 53 

snap,  construction 93,  94,  96 

sub-base  required , 93 

stage  flue  control,  type  required 112 

street  railway 145,  150,  151 

tests  for 95 

time,  metal  cabinets  required  for 94 

wood  blocks  required  for 94 

Switchboards,  construction 14 

free  from  moisture 15 

ground  detectors,  when  required 15 

installation 15 

instrument  circuit,  protection 15 

fuses 14 

link  fuses  permitted 14 

marine,  requirements 159 

rear  connected 15 

space  back  of 15 

wiring  for 13,  14 

wood,  when  not  permitted 106,  159 

permitted 14,  15 

Systems.     See  Sections. 

Tape 29,  156 

Terminal  blocks,  generator 11 

Testing,  fixtures  for  grounds 125 

insulation  resistance  in  completed  buildings,  Table  31 200 

transformers 24 

wires.     Tables  5,  6,  7,  31 171,  172,  173,  200 

Theater  wiring,  arc  lamps,  portable,  construction Ill, 112 

auditorium  lights 106 

borders,  conductors  required 107 

construction 107,  108 

trough  suspension 107 

wiring  to 107 

bunch  lights 108,  109 

cable  border,  construction,  Table  16 186,  187 

stage,  construction,  Table  16 186,  187 


INDEX  229 

conduit  required  switchboard  to  border 107 

cut  outs,  receptacle  limits  on 106 

wattage  limits 106 

dressing  rooms,  lamp  guards  required Ill 

pendants Ill 

exit  lights,  control 106 

fuses  on 106 

emergency  lights 105 

foot-lights,  construction 107,  108 

flexible  cord,  ampere  limits 110 

type  permitted  in  dressing  rooms Ill 

festoon  lights 1 10 

guards,  lamp,  required 110,  111 

lights  on  scenery 110 

motor,  curtain,  type  required 108 

operator,  competent,  required 112 

pin  plug  connectors 109 

plugs,  stage 108 

plugging  boxes,  portable 109 

proscenium 107,  108 

receptacles,  number  on  one  cut  out 106 

wattage  limits 106 

stage,  approved,  required 108 

control 108 

rating 108 

wiring  requirements 108 

service,  auxiliary,  required 105 

wires , 105 

scene  docks 108 

special  electrical  effects 110 

stage  flue,  control 112 

stage  work 106 

strip  lights 109 

switchboard,  guard  rail  required 106 

wooden,  not  permitted 106 

wire,  border,  insulation .' 107 

Table  16 186 

wires,  service 105 

Tables,  Section  9 163 

Transformers,  approved,  required 25 

Note  12 24 

enclosures 24 

grounding .' 23,  25,  33 

installation,  electric  sign 129 

high  potential 24 

extra 24 

low  potential 24 

Section  2 23 

low  voltage 25 

wireless  telegraph 46 

tests.  .  .  ....  24 


230  INDEX 

Tubes,  cabinets,  entering 67 

construction,  Table  19 190 

cross-over 67 

electric  signs 116 

entrance 29,  58 

signal  systems 41 

marine  stuffing lt>8 

signal  system 42 

timbers  passing  through 67,  72 

wall,  through  brick 58 

Tubing,  flexible 72,  73 

Underground  conductors 36 

Underwriters  laboratories,  organization  and  purpose 2 

Wattage  limits,  circuits,  2-wire 58,  60 

3-wire 60 

cut  outs,  branch 61,  115,  116,  118,  123,  156 

railway  systems,  lamps. 147 

switches,  single-pole  on  neutral 94 

switchboard  instrument  circuit 15 

Wire,  armored.     See  Cables,  Armored. 

concentric,  Table  8 175 

conduit,  Table  8 174,  175 

fixture,  Table  9 176 

flexible  cord 129 

lead  covered 13,  58 

iron,  use  of,  signal  systems 43 

netting  on  arc  lamps 51 

rubber  covered,  0-600  volts,  Table  5 171 

600-3500  volts,  Table  6 172 

3500-7000  volts,  Table  7 173 

slow-burning,  Table  3 170 

slow-burning,  weatherproof,  Table  2 169 

Wires,  allowable  capacity,  aluminum 57 

alternating  current 18 

Table 168 

rubber  covered 57,  58 

Table  1 168 

attics  in 66 

border  insulation 107 

concealed  work,  spacings 65,  67,  71 

conduit,  different  systems  in  same 78 

conduit,  installation 77,  78 

circuits,  allowed,  in 78 

crossing  pipes 67 

cut  out  required  at  change  of 93 

elevator  shafts,  in 68 

entrance 29,  31 

entering  cabinets .   67,  71 

extra  high  potential,  installation  of  primary 58 


INDEX  231 

insulation  of  secondary. 58 

pole  line 34,  36 

fished 71,  72 

fixture,  braid  test  for 124 

must  be  tinned 123 

on  exposed 123 

protection  of 126,  127 

slow-burning,  approved 127 

stranded,  required 124 

flame  proof  required 19 

flexible  tubing,  in 71,  72 

Note  25 72 

fuse  required  at  change  of 58 

generator  to  switchboard 14 

grounded  neutral 60 

grounding,  A.  C.  secondary 31,  32,  33 

Note  14 31 

grounding,  at  central  station 32 

grounding,  inside 32,  33 

grounding,  neutral 31,  32 

grounding  outside 31,  32,  33 

Note  14 31 

guard  strips  required 69 

inside  work  spacings 52,  65,  66,  70,  71 

knob  and  tube,  insulation  required 70 

knob  and  tube,  concealed 71,  72 

knob  and  tube,  open,  spacings 65,  67,  71 

mixed  system 66 

moulding,  in 73,  78 

neutral,  single  pole  switch  on 94 

not  permitted  under  staples 32,  68 

outline  lighting,  type  required 115 

passing  through  timbers 72 

protection  against  mechanical  injury 69 

Notes  23,  24 69,  70 

rheostat  insulation 90 

rubber  covered,  type  letter  for  0-550  volts 57 

rubber  covered,  required,  electric  cranes 135,  137 

electric  signs 118 

fixtures 124 

high  potential  circuits 13 

inside  work 52,  71 

moulding,  wood 73 

outline  lighting 115 

pole  line 29 

railway  system 144 

service 29 

signal  system 43,  45 

theater  work 110 

series  arc,  insulation 52 

signal  system,  ground 45,  46 


232  INDEX 

entrance 137 

insulation 43 

installation 43,  44 

on  cross  arms 43 

permitted  under  staples 42 

Note  17 42 

pole  to  building 43 

underground  conduits 43 

slow-burning  permitted 67 

smallest  size  permitted,  electric  signs 118 

elevator  conductor 131 

fixture 123 

ground  detector 15 

grounding  lightning  arrestors 16 

electric  cars 150 

metal  moulding 85 

metallic  protective  system 84 

neutral,  central  stations 32 

secondaries 32 

signal  system,  protective  devices,  ground 45 

3-phase  systems,  ground 32 

wireless  telegraph  apparatus,  ground 40 

interior  work 57 

marine  work 1 55—1 58 

moving  picture  arc  lamps 113 

railway  systems 143,  151 

signal  systems 42 

stranded,  computing 57 

required 124 

soldering  required 67 

subject  to  acid  fumes 67 

to  heat 57,  67 

to  moisture 66 

support  of,  at  end  of  runs 70 

service,  aerial 29 

conduit 31,  33 

defined 31 

knobs  permitted  on 30 

petticoat  insulators  required  on .> 30 

support  of  outside 30 

wood  blocks,  painted 30 

switchboards,  installation  at 13 

tie 68 

tinned,  all 123 

Tables  8,  9 174,  175,  176 

twin,  use  of 70 

Wiring,  car,  read 142-151 

moving  picture  shows 113,  114 

theaters 105-112 

Wireless  telegraph  apparatus 46,  47 

Wooden  moulding 73,  74 


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ENGINEERING  L 


NOV  29  L  .-  tit 
11950* 


LD  21-100m-12,'46(A2012sl6)4120 


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